ATC SCM40 active - DAC vs dedicated preamp

[crandell]

Hi!

I just took the plunge and moved from ATC passive 19s to the active 40s. What an amazing speaker! I am currently running an Auralic Vega G2 direct to the active 40s. So the Auralic is wearing many hats streamer, DAC, and preamp. My question is if there would be any benefit by adding a dedicated preamp. The Vega G2's volume is in the analogue domain I believe. With the pandemic impacting us all, I haven't had the opportunity to demo any preamps so I am hoping to get feedback so I can keep an eye on the classifieds (demo may be a challenge in that case so looking for others experience). Any thoughts and potential preamp recommendations for the active 40s (if there are benefits) are greatly appreciated. Thanks and stay safe everyone! Chad

[Mariner]

Hi Crandell,
At first congratulations to your speakers!
From my point of view every unit more in your system is a hurdle the signal has to pass,
and your Auralic DAC is a fantastic unit, so why will there be a benefit in adding one more?
If the Auralic has all the inputs you need, from my point of view it makes no sense to add an additional preamp.
But this are only my "five cent"!

[Gandalf]

Hi Crandell,

It must be exciting for you for the upgrade you have made. Out of interest what extra benefit would you get if you obtained an dedicated preamp?

[linger63]

IME using a dedicated Pre Amp (ATC CA2 MK2) with active ATC's is a clear step up from using a DAC/PRE (Benchmark DAC2)

Benefits include bypassing the DAC's digital volume control which avoids bit stripping.

Also an ATC pre matches up better as it has a very low output impedance. ( the amps in your SCM40's are 1V sensitive!!!!!)

Last of all..............it simply sounds much better as your actives are getting driven properly.

I understand the "less is better" camp and was once in it but............not anymore.

Anyway just my "five cent" too............like Mariner....🙂.

Don't forget to use quality I/C's and AC cables as ATC actives can highlight differences easily.

[crandell]

Thanks for the replies everyone.

Mariner - Thanks the actives are a wonderful upgrade! The Auralic has all the inputs I need at the moment and it is a fantastic DAC so it would be great to keep other cables and components out of the chain so I like your response because it keeps me from spending more money.

Gandalf - that is the magic question, is there a benefit.

linger63 - Thanks for providing your experience because the Benchmark units seem to be very highly rated and quite capable as a preamp so knowing you did get a benefit makes the debate more challenging. The one thing I was concerned about was the output of the Auralic. It outputs 4.8V's which would seem hot for the 40s. I did dial that back -6db via the software so that should reduce the voltage to a more manageable load but probably not as good of a match as the ATC pre's. The volume on the Auralic is analogue I believe so I shouldn't have the sound impacts as I have read when in the digital domain when running at lower volume (not that I have a good technical understanding, just from my reading!). The ATC pre's must be a match made in heaven. I wish I could demo some of their units but there is no place close by.

I appreciate the thoughts everyone!

Chad

[fr.jazbec]

Hello, I am Rüdiger from Germany, so sry for my bad English.
I can‘t find the output impedance of the Aurealic G2. I think it should be as small as possible.
Here in my musicroom I use an Audionet Pre1G3+EPS Preamp to drive my ATC SMC100ASL and it is a very good Combination. I am using the unbalanced outputs with a Cinch/XLR adapter cable(Sommer Carbokab)because ist sounds better(clearer with more air)than the balanced connection.
Kind regards Rüdiger

[gregmelb2]

According to the spec sheet the balanced output is 5 ohms and the unbalanced output is 50 ohms for the Auralic G2

[crandell]

Thanks Rüdiger! I haven't heard of Audionet, I will need to look it up. Interesting that the unbalanced is working the best for you.

[simonthepieman]

Hi!

I just took the plunge and moved from ATC passive 19s to the active 40s. What an amazing speaker! I am currently running an Auralic Vega G2 direct to the active 40s. So the Auralic is wearing many hats streamer, DAC, and preamp. My question is if there would be any benefit by adding a dedicated preamp. The Vega G2's volume is in the analogue domain I believe. With the pandemic impacting us all, I haven't had the opportunity to demo any preamps so I am hoping to get feedback so I can keep an eye on the classifieds (demo may be a challenge in that case so looking for others experience). Any thoughts and potential preamp recommendations for the active 40s (if there are benefits) are greatly appreciated. Thanks and stay safe everyone! Chad

Yes doing the same VegaG2 into active 40's sounds brilliant, I use roon with it and just signed up to Qobuz for Hi res streaming (the subcription was on offer ) It really is good
and not struggled to find anything on the platform yet plus the suggestions are brill for finding new music etc.
As the G2 also has an analog input I use a GyroSE turntable too through it, I think it works very well as a preamp no need to add anything I would say 😀

[simonthepieman]

IME using a dedicated Pre Amp (ATC CA2 MK2) with active ATC's is a clear step up from using a DAC/PRE (Benchmark DAC2)

Benefits include bypassing the DAC's digital volume control which avoids bit stripping.

Also an ATC pre matches up better as it has a very low output impedance. ( the amps in your SCM40's are 1V sensitive!!!!!)

Last of all..............it simply sounds much better as your actives are getting driven properly.

I understand the "less is better" camp and was once in it but............not anymore.

Anyway just my "five cent" too............like Mariner....🙂.

Don't forget to use quality I/C's and AC cables as ATC actives can highlight differences easily.

I used a Benchmark DAC2 HD something version, prior to the Vega. The Vega is miles better as its an actual pre-amp also not just a DAC with a volume
control.
I think the ATC + Vega G2 is a stellar match . They work exceptionally well.

[Dogill]

Also note Jason Kennedy's review of the ATC100SE who found the ATC preamp CA2 very beneficial

[highstream]

I have SCM19A's. For several years, I ran straight from dacs -- PS Audio DirectStream and now Lampi TRP, both with volume control -- straight to the speakers, thinking it would be more direct, simpler and cheaper. Just about everyone I asked, except Lampi NA, said that adding a preamp would be better. First with a PrimaLuna Dialogue and now with a Supratek Chardonnay, I've found that good advice. There's more gain, the sound's better and with tube rolling I have an additional element of tonal control, tho more complicated with two tube units -- and more money. I have to say, though, that some people find the direct route better. If you can audition a pre to find out for yourself, it wouldn't be a bad idea.

[arzojaan]

Also note Jason Kennedy's review of the ATC100SE who found the ATC preamp CA2 very beneficial

Such Special speakers need at least a top SCA2 preamp))

[9radua1]

Check up on what kind of benefits you are expecting from inserting a preamp in your digital system. Be precise. What are you missing now? You need to know what you’re buying SQ wise, otherwise you’ll be prone to subjective bias (like all of us) because “new must be better”. On paper, there shouldn’t be any difference as long as the preamp is transparent and the impedance and voltages match, which they will for almost all modern DACs with volume control. (PS. Modern digital volume controls don’t strip off bits, since they run floating point now.)

My advice is to take a step back and find out what exactly it is you’re looking for. And is a preamp the right answer to achieve that. Might acoustics be a better place to invest, for instance?

Happy hunting 🙂

[fr.jazbec]

Thanks Rüdiger! I haven't heard of Audionet, I will need to look it up. Interesting that the unbalanced is working the best for you.

I think the reason is the unbalanced design of the Audionet. They need a additionally step to bring the unbalanced signal into a balanced one and perhaps this makes the sound a little bit closer. But the difference is very very small and perhaps it’s only in my mind.😉
This ist the Audionet Pre1G3 Preamp

http://en.audionet.de/machines/pre-i-g3/

[hifidy]

Preamp does color the sound... It really depends on your taste and set up. The best way to do it is to borrow a preamp for audition before making any purchase. I have tried a couple of preamps (from active to passive) and finally settle with a Bricasti. Passive preamp is not a bad choice as well if your source output enough voltage or gain.

[gregmelb2]

I think I fall in the preamp (provided it is a good quality one) is better option especially if it has adjustable gain.
I also read the Jason Kennedy review in Hi Fi+ that Dogill mentioned and using the preamp was a major improvement with driving the ATC Scm1OOse.

[PeteT]

I've only just joined but I have owned Active 40's for almost 3 years and love them. I previously had passive 19's powered by Naim 250DR which I also enjoyed greatly but Active is something else . I started with a Benchmark DAC3 HGC which is very good indeed . I became interested in a dedicated Pre amp because the Benchmarks Pre Amp definitely had a sweet spot higher up the volume range , this was explained to me by Benchmark as the position with the best signal to noise ratio . Just before Xmas last year I got a home trial of an Auralic Vega G2 , attracted largely by its lauded analogue Pre section . The sound quality was exceptional all across the volume range and the only problem was I didn't put my order in then as I went away January and then shortly after my return we were in lockdown . Thankfully my patience paid off and i now have one of the first Vega G2.1 DAC's here , the sound and synergy with Active ATC is amazing . I wouldn't dream of adding a Pre Amp to this set up due to the wonderful Vega volume control .

[darrenyeats]

In short, it depends on how well the digital volume control is implemented, and the sensitivity and impedance matching between DAC and actives.

Many ATC actives are fixed to 1V input sensitivity, which is tricky since most DACs output 4V over XLR. Some ATCs can be adjusted to 2V input sensitivity, which is a bit better. I never really understood why ATC do this ... these voltages should be about double to match better the conventions for domestic DACs (plus studio line level equipment can have even higher voltages). This is particularly important with a digital volume control.

Also, good preamps have a very low output impedance, it's harder to find DACs with the same.

Two notable manufactuers of DACs with XLR outputs capable of low voltage and at the same time low impedance output, are Weiss and dCS. I take this as a sign I'm beating the right drum. (That said my ideal DAC would have 32 bit high rate input and a NOS mode so I could do my own filtering but I'm in a small demographic there!)

If the DAC isn't providing good sensitivity and/or impedance matching, or if it has a non-optimal digital volume control (e.g. undithered) then I wouldn't be surprised that a preamp helps.

[jophill]

In short, it depends on how well the digital volume control is implemented, and the sensitivity and impedance matching between DAC and actives..

Yes indeed, but I would say that the same two considerations apply whether using a preamp or a DAC. What constitutes good engineering may be different in the two cases but I am not sure I can see why one case should be inherently better than the other.

In reference to just the volume control, makers of audio kit know that users have remarkably varied requirements. Amongst other things this includes their desired ranges for audio loudness, differently sized listening rooms, the mean levels from their various sources, and highly variable content peak-to-mean ratios. The volume control is the place where this uncertainty is all ironed out.

A quick addition I did of the potential ranges that users may demand suggests a volume control may have to deal with 40 dB range from one extreme (right up) to the other (down at the point where it gets too sensitive to be usable). So, a good volume control is, IMHO, a sine qua non of either a DAC or a preamp. Different engineering but the same goals, I think.

Many ATC actives are fixed to 1V input sensitivity, which is tricky since most DACs output 4V over XLR. Some ATCs can be adjusted to 2V input sensitivity, which is a bit better. I never really understood why ATC do this ... these voltages should be about double to match better the conventions for domestic DACs (plus studio line level equipment can have even higher voltages). ...

I currently feel you are right, but I am beginning to think about a purely intellectual lockdown project with a spreadsheet, just to see if I can understand with some use cases where I would centre the sensitivity of an active loudspeaker.

Regards

John

[AlastairH]

Hi Chad,

I hope you are still enjoying your set up.

There are some excellent points here made both technical and subjective, I’d just like to echo what has been said already in terms of demo. Try as much as you can without having to spend and don’t rush.

I had a similar time running through a Meridian Pre, ATC pre, direct from a Mytek Brooklyn and a dCS Elgar Plus Dacs, then trying those dacs through the pre amps. I can’t recall the outcomes now other than I had a mismatch in terms of volume control range vs big jumps in volume when using the ATC and Meridian pres.

That aside I could ultimately enjoy any of the options but generally preferred to go direct from the DACs to 100ASLs because of the volume range and it involved one less box which is just more practical for me. I really did not need a pre to serve anything other than one analogue source (the DAC). My work around when using pre amps was to use Rothwell Attenuators in order to go above 9 o clock without blowing my ears out. That opens another debate in terms of the impact of attenuators.

I am into surround sound so the Meridian 861 I use now serves multiple functions including some gentle filters for bass (to tame some excess) as well allowing calibration of the volume (for surround sound). So I have a nice range to play with. As to bit losses, yes there might be some at the lower volumes (I do think this is the case) but it does not bother me.

The great news is that you likely (budget permitting) have a lot of choice. And hopefully any final decision made will have been an enjoyable experience to get to!

Alastair