Many people have strong opinions about using pre-amp or not. I am in the latter camp, which is an easy spot to land if you only have one source (in my case, Roon/Rossini). While this has been covered in other threads, I note that dCS runs direct to power amp, at audio shows and in their UK factory listening room. So… if it’s good enough for them, it’s good enough for me ; )
James helpfully shared previously that dCS has four power amps in-house: Constellation, D’Agostino, dartZeel and VAT. While I am not tracking this statistically, I see the D’Agostino combination most frequently in pictures.
I don’t think these choices are half as portentous as you make out @keiserrg.
dCS chooses to demo their equipment without preamps in much the same way that art galleries tend to have plain white walls and no windows. They just want you to focus on their product, they want to keep the “supporting cast” as small and inconspicuous as possible.
Of course preamps change the sound, the best ones only subtly, some will change it for the better and some for the worse. There is no universal “right answer”.
dCS’s choice of demo amps has been explained many times. It loosely reflects the demographics/preferences of demo room visitors, constrained by storage space etc. Is it hugely significant that other top flight brands like Soulution, Boulder, Vitus etc aren’t represented? Exactly.
Of course “if it’s good enough for them” is one approach one can take if one is unable to compare oneself, or doesn’t want to. It certainly makes life simple and is unlikely to lead to any bad combinations. But will it lead to the best and does is imply that others are inferior? Exactly.
Wilson speakers don’t suit my sonic (or aesthetic) tastes at all. But lots of other folks swear by them and that’s great. I’ve found it hard to form an opinion on the d’Agostino amps for the simple reason that I can’t recall ever hearing them demoed with speakers other than Wilsons.
PS is VAT a new JV between VAC and BAT? I think you mean VTL.
It’s interesting that many dCS users hear the benefits of separating functions into dedicated units with their own power supply and housing culminating in the Vivaldi stack, yet when it comes to preamplification this would no longer be the case?
I think the output stage in a dCS DAC board is quite good, just not as good as a separate preamp can be. This depends on the level of the preamp, and the synergy of the equipment and cables. Having a discussion in terms of coloration is just not the whole story. There might be power amps that have good results directly connected, yet I feel there are a lot of us who feel a high quality preamp is still better.
One very important job of a preamp is to be a buffer between different loads (impedances). Although the dCS output stage has very good capabilities it is not as well suited as a dedicated preamplifier can offer. That’s my 2 cents.
The AHB2 is an absolute giant killer. I remember hearing an interview with Bruno Putzeys where he said that the only amps in the world that measure as well as the Eigentakt are the AHB2 and the Boulder 2150s. John Atkinson agreed:
The combination with the Harbeths must be absolutely stunning.
Funny you should mention Boulder as this is the only other amp I’ve heard that has a similar ‘nothing’ character. (my dCS dealer is also a boulder dealer). They have them hooked up to large Rockport speakers. I thought I would hate the combo. I was totally wrong - the system sounded sublime even at low listening levels
The electrical interface between a Preamp and an Amp requires the former have an output impedance as low as possible, while the latter has an input impedance as high as possible. An ideal pairing would have 0-Ohms output impedance on the Preamp and infinite-Ohms input impedance on the Amp.
Very few discrete Preamps come close to dCS DACs for output impedance; the Vivaldi for example, has a (balanced) output impedance of 1.3 Ohms! Most Preamps are a 100 times that. Thats just one of the reasons why dCS DACs work so well connected directly to Amps.
That said, I do agree in certain setup, especially where the Amp has a lower than preferred input impedance, the addition of a Preamp can be quite beneficial.
Anup’s excellent posting concerns the appropriate electrical engineering principles for the optimum transfer of the signal from source to power amplifier. However I would add that the choice between a preamp and no preamp for home listening purposes may also involve an aesthetic decision, necessary because recordings themselves vary considerably and are generally made to meet commercial rather than audiophile considerations.
Echoing Pete, this passage in Boulder’s technical paper on the 2160 Power Amplifier also supports @Anupc 's helpful post:
Boulder 2160 Technical Paper
The input circuit is a true, full differentially balanced, three-stage, instrumentation-style circuit initiated with three-pin XLR connectors. This ensures that the audio signal passes from the source to the amplifier free of distortion and noise by keeping the input impedance as high as possible in comparison to the output impedance of the source. Input impedance is a tested and verified 200k ohms (100k ohms per leg). This high input impedance ensures a much greater resistance to noise and also provides flat frequency response.
Thanks Keiserrg. Yes, I am aware of this. It is correct and is the engineering reason that Anup made earlier. Please read my comment again as I am making a further point. It is that unfortunately the recordings that we listen to in pracrice are imperfect as they have to meet the needs of the general market . Therefore in making decisions on system componens an aesthetic point of view also has a bearing on the matter.
I am another user who was shocked to find out that Naim’s 552dr preamp (price now £27k ?) was beaten by Rossini Apex volume output. It’s not just "high end " Naim preamps that have been beaten by the digital volume output of the Rossini.
Surely dCS must be doing more than providing a low impedance output for the power amp? Otherwise all DAC manufacturers could do that and encourage more customers to spend more money on their DACs by selling their preamps and reinvesting their money in the source.
That’s exactly what I did; sold my AR Ref6SE and Melco N1ZS10 an purchased an Aurender W20SE to slave it to my Vivaldi Apex which now goes direct into AR Ref160S…
I tested my Rossini Apex straight into Nagra poweramp (XLR) but my pre-amp (Nagra with tubes) gives me much more SQ.
Guess it really depends on you setup.
Of course a Vivaldi could be different animal regarding analog output stage …
Interesting conversation and myself, @all2ofme , and @magicbus have been discussing this in relation to our dCS and DarTZeel setups.
DarTZeel is designed for single ended RCA use (even though 1 XLR input is provided on the preamplifier). Despite dCS maintaining their preference for the balanced XLR output on their boxes, we have preferred using RCA out into our DarTZeel’s. It boils down to deciding to follow dCS or DarTZeel’s preference - and we have decided we prefer the single ended DarTZeel way.
DarTZeel also provide other single ended inputs via their “ZEEL” connection which utilizes 50 ohm coaxial cable (the famous ZEEL cables). @magicbus has had an eye opening result using this connection.
Several emails with Herve’ Deletraz yielded the following comments about the Zeel connection:
“By the way, be aware that unless the source, the cable AND the target (the receiver) are not all of 50-ohm impedance, the match will not be completed. The fact that an output impedance is given for 50 ohms does not implies that it can drive a 50-ohm load without issues. I wasn’t able to check this with dCS gear.”
Checking with dCS indicated the RCA output of our boxes present an impedance of 51-52 ohms - in other words a precise match maintaining a straight 50 ohm impedance from dCS out > Zeel 50 ohm cable > 50 ohm DarTZeel preamp impedance (and even 50 ohm impedance for the DarTZeel amp if one wishes to eliminate the preamp)
This is just me rambling on (most of this is beyond my pay grade) however in light of some of the impedence matching banter in the above posts it sounds like we are encountering similar things with our dCS/DarTZeel match.
I have just received back the totl Chord Music cable which has been re terminated RCA/RCA and I cannot imagine the connection between my Rossini and DarTZeel preamp getting any better than this. @magicbus is comparing a 50 ohm Zeel style coax cables between his Vivaldi and DarTZeel integrated to his Chord Sarum T RCA cable (one level below my MUSIC cable) and he prefers the 50 ohm connection.
with all the talk of using dCS Dacs as pre amps, there doesn’t seem to be any easy way (if at all) for a dCS Dac to trigger on and off power amps. a 12v trigger on future models would be nice!
Just my personal opinion, adding an external physical 12V trigger to the dCS Systems would be a big step backwards in costs and aesthetics. So, no, please.
A modern automation system to trigger your amp separately through other means when the dCS system is turned on - Crestron, Control4, Extron, Alton, etc.- would be much better. Or even any one of those dozens of cheap and cheerful external IR/Home-Automation to 12V trigger boxes would be better.
point well taken on the costs and aesthetics of adding the 12v triggers to dCS products. However implementing some of those pro automation solutions would cost more than my amp !
Anyone know of a simple off the shelf IR to 12v relay trigger that doesn’t involve wiring stuff up? Most of what i found with a quick web search looks like a high school electronics project!
!