Jeff Rowlands Amp and Dac vs. VAC amp and DAC


Hello, I am new to this forum but I have a question. I am trying to pair an amp + DAC with my Wilson Sabrinas. I have listened to Jeff Rowlands integrated with the Aeris DAC. And the VAC Sigma integrated with the Aeris DAC. Price is a factor and so is space. Does the 625 need a pre-amp? Any suggestions or thoughts? 
rinpoche
Do you have suggestions for other amp pairings with the Wilson Sabrinas? I am open-minded at this point.
I suspect that Knghifi’s suggestion of the VAC 200iq would avoid the concerns I expressed about pairing the Sigma with the Sabrina. Especially if two of them were used as monoblocks, but possibly also using just one in stereo mode. I say that in part because the 200iq includes a third output tap, designated as being for 1 to 2 ohm loads. That in combination with the reference in its description to 6 db of feedback suggests that the output impedance of that tap is low enough to avoid the tonal issue I referred to. It is also more powerful than the Sigma, of course.

A risk of going that route, however, would be the possibility that having a preamp in the chain might ultimately prove to be sonically desirable, and a preamp that would do justice to the rest of the equipment would add up to very big $ in combination with two or even one of those amps. See this thread for some discussion of using the Aeris with and without a preamp.

From a technical standpoint I would also expect something like an ARC Ref150SE to be a compatible pairing. ARC tube amps tend to have lower output impedance than many or most other high quality tube amps, as well as having very robust power supplies. However its size, complexity, heat generation, cost, and again the possible desirability of a preamp may rule it out. And I have no knowledge of how well its sonics would synergize with those of the Sabrina.

I’m not particularly knowledgeable about VTL products, but the fact that most of their amps have only a single output tap, nominally rated for a 5 ohm load although claimed to be suitable for 2 to 8 ohm loads, would give me pause.

Regarding Rowland solid state amplification, I have no experience but FWIW a number of members here whom I consider to be particularly credible, including Ricred who posted above, use it with great results. As far as I know there are no technical issues that the Continuum S2 or the Rowland power amps would present in your application.

Good luck. Regards,
-- Al

There is a VAC Phi 200 used for sale. I could pair that with a new VAC pre-amp (an entry model) if you think that might help with the issues you are describing. Wilson Audio approved the Sigma SE but that doesn't mean they have paired them. In terms of an in-home audition, I think this is a very good idea. The Rowland gear is, I think, less of a problem but I would loose that magical tube sound. Yet, I would gain in ease of use and given I will be adding in TV, maybe that is a good thing. See why I started this thread!!! It is like comparing two delicious desserts, and you can't eat both of them. Would love more of your excellent thoughts on this!! Thanks
Although the specs on the Phi 200 aren’t complete enough for me say with any certainty, I suspect there is a good chance it would avoid the issues I raised about pairing the Sigma with the Sabrina. For that matter, I can’t be sure that the issues I cited would be problems with the Sigma either, but they are certainly significant concerns IMO.

Probably the best thing to do if you want to consider the Phi 200 is to call Kevin Hayes at VAC and discuss it with him. In doing so, be sure to point him to the Stereophile measurements of the Sabrina that I linked to. The question, basically, is not whether the amp can drive the speaker, it is whether or not impedance interactions would cause the pairing to not be a good one in terms of sonics.

However another concern that just occurred to me, that is applicable to the Phi 200, the 200iq, and most or all of the other VAC power amps, is that they have particularly high gain, while the Aeris DAC has a specified maximum output level of 7 volts, which is extremely high. (It isn’t clear, though, if the 7 volts applies to the balanced output, the unbalanced output, or both).

The gains of the VAC amps are about 5 db more than the gain of the Rowland 625 S2, assuming balanced connections are used in both cases, even though the Rowland is much more powerful. (And the gains of the VAC amps from their unbalanced inputs are even higher). The combination of high amp gain, very high DAC output, and the additional gain of an active preamp (if one is used) may cause you to have to set the volume control(s) on the DAC and/or preamp to settings that are undesirably low in their ranges. Which, in addition to possibly compromising the resolution of the volume adjustment, might degrade the sonics of the DAC, especially if its volume control function is performed in the digital domain.

Although on the other hand the somewhat low sensitivity of the Sabrina will be helpful in that regard, to some extent.

Apologies for citing so many concerns and negatives in my posts, but as I see it these are things that should be considered before making such a significant investment.

Regards,
-- Al

I am very appreciative. I did write to Kevin and he thought the Sigma would be great. He also said the Phi 200 would be great, but both would be excellent choices. The used Phi, however, would not be warrantied as far as I understand because it is coming from the US to Canada, so that sort of stopped me from pursuing it fully. As I mentioned, I don't have experience with tubes. This is a new adventure for me. I am a bit nervous but also trying not to be intimidated (as a woman I am not as sure about biasing and rolling and tweaking tubes -- yet, but I am sure I will learn). All of your suggestions are valuable. The best thing would be if the store would come to my house to audition the JR and VAC amps. That would be great. Are there any other amps I should be looking at that will be reliable and easy to run in this price range (with the Sabrinas)? 

First off, Al's comments are very informative and much appreciated. Secondly, I only comprehend Al's comments at a layman's understanding.

So, with that in mind, I have heard the Sabrina's twice. And both times I was pretty enraptured. The first time was with D'Agostino mono blocks and preamp with a Bricasti M1 DAC. Not sure of wire and other ancillary items, but this absolutely hit the nail on the head for me. This was at The Show Newport 2015. My friend and I both thought it was a very lovely sound. Certainly in the best five or six rooms.

I also more recently heard the Sabrina's with an ARC GSi75 integrated amp. So, different room and supporting cast, but again, wow, what a nice full rich sound. Tube magic in evidence. The ARC has its own DAC, which I think they used, and this was a very nice complement for the Sabrina's. For only 75 wpc, these tube amps had an iron grip on the bass and I was pretty astonished as were others as well. I heard them at at a high end get together and there were a number of people who felt this was one of the best setups in the room; there were 6 or 7 total and they were nearly all Wilson with ARC gear. This particular Sabrina/ARC GSi75 integrated pairing also one of the least expensive at that get together.

I still think a lot about the Sabrina's with an ARC GSi75 integrated or the D'Agostino gear. Very nice indeed. My one caveat concerning the Sabrina's with an ARC GSi75 integrated is that the amp takes 45 seconds to power on and since my system is used with TV/Movies as well, that'd be a no go as my wife would not accept that. Never hurts to dream though.

BTW, most of the time I have seen the Wilson line displayed they were being paired with ARC gear. I have heard most of the floor standing line and I thought the Sabrina/ARC GSi75 integrated was near the best. On that same day I heard the Alexandria XLF with D'Agostino mono' and pre and it was very engaging but to me the cost differential seemed unjustified. Of course, this is just my own opinion. Good luck in your journey, hope it is a lot of fun for you.