Perfect combo! I don't recommend tubes for the Q5.
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Very interesting question and combination. Unfortunately, I don't have direct experience with the XA200.5 and have only heard the Q5 twice, briefly, so my comments may be meaningless to you. However, I'm a big fan of both Pass and Magico.
As you, I love Pass class A amps and have owned the Aleph 3, 5, 2, the XA160, the XA100.5 and now the XA160.5. The XA.5 is clearly better than the previous models.
I also own Magico speakers, the Mini2. The XA160.5/XP-20/Mini2 is an excellent combination in my smaller room. The Mini2 is a difficult load, but my room is small and the 160.5 sounds much better driving the Mini2 than did my old 100.5 (320 vs 200 watts in class A at 4 ohms). I think the purity of the Class A 200.5 with the ultra low distortion of the Q5 could be very good, but I don't know if there will be enough power for your rather large room. Here's why:
I heard the Q3 at Goodwin's in Boston in their large room. I think it is about the size of your room and they felt their normal amps for the Q3 (Spectral 360, I think) could not adequately drive the Q3 in their large room, so they showed it with 1000WPC Boulder monos. It sounded amazing. Now the Q3 is a smaller speaker and more efficient than the Q5 and it needed that amount of power in such a large room according to the guys at Goodwins. Alon Wolf was also their for the debut, so I'm sure he approved of the choice.
I have heard the S5, Q3 and Q5 all in the large room at Goodwins. The Q3 is my favorite. I listen almost exclusively to acoustic and small scale jazz and classical. The Q is more refined and tonally neutral than the S5, IMO. The S5 is slightly warmer with more bass slam, and punch than the Q3, so if I also listened to a lot of rock and other amplified music, I might save the money and buy the S5. I found the Q5 a bit on the cool side compared to the Q3, but I'm sure it has more extended bass.
Your dealer's XA160.5 and Q3 is my dream combination for my smaller room. I would love to hear that pairing with my analog. What's the name of your dealership? There are not many that carry both Magico and Pass Labs.
You have an fun task ahead of you. Have you considered the Pass XS amps? Given a high enough budget, the XS300 may be a near perfect amp for the Q5.
Thanks for the post. I have paid attention to your comments in the past and was hoping to get your feedback.
My problem is I have heard the Q3's resolution and simply can't imagine any speaker satisfying my personal tastes more (with the sole exception of its lower register voicing). However, as you point out my room would only exacerbate this low-end deficiency.
That said, I have not yet heard the S5, but fear the resolution compromise may be an issue. You can treat a room to gain bass, but resolution lost is gone forever.
Interestingly the XS-300 is reported to output 50 amps max on the Pass web site; the XA200.5 puts out 48 amps! I wish I had a clearer understanding of how that current would drive the Q5's. Comments from Q5 owners are appreciated. (Remember the XA200.5 is essentially the same amp as the 1000 watt X1000.5 but biased in Class A.)
Of course volts mater too!
I can't comment on the sonics or synergy of the components and speakers that have been mentioned, but I would make the following points:
1)The GAT preamp has a specified gain of 25 db, which is most likely way too much for use in this and the majority of other applications involving digital sources. Unless, that is, the optional volume controls that are offered with the MSB DACs are included, and provided that those controls do not adversely affect sound quality when set to provide substantial amounts of attenuation. In which case, however, there may be no point to having a separate preamp at all.
The gain of the XP-30 is 10 db, btw, which is much more reasonable.
2)I wouldn't attach much significance to the 48 and 50 ampere current specs. (BTW, the manual for the Xs-300 indicates 48 amps, as opposed to the 50 amps indicated on the web page). As with most amplifier output current specs, they presumably represent the amount of current that can be supplied for an unspecified tiny fraction of a second into a dead short (i.e., 0 ohms), and therefore are not all that meaningful when it comes to driving music into real world speaker impedances.
Consider, for example, that for the sinusoidal waveforms upon which these kinds of specs are based 48 amps peak corresponds to 48 x 0.707 = 33.94 amps RMS, which into a 4 ohm resistive load corresponds to (33.94 squared) x 4 = 4608 watts! Clearly 48 amps is overkill even for the Q5's somewhat difficult impedance characteristics, and would not be attainable anyway due to voltage swing and other limitations.
Good luck as you proceed. Sounds like you're on the road to a really fine system. Regards,
Thanks much for your comments. They will definitely prompt some additional caution and thought on my part.
Regarding point (1): I originally was directed to the Conrad Johnson GAT and ARC Ref 10 (12 db of gain) by a representative of at Pass as a preamps with good synergy, but I didn't address the digital source with him. I will now. Thanks.
I have been aware of the GAT's 26 db gain and have wondered about this issue but given the Pass XA200.5's fairly modest 26 db, I thought it might even be to my advantaged with the tough Magico Impedance curve. But your right, the MSB DAC outputs 3.6 volts single ended and should be considered. Regarding gain adjustment, I do not want to attenuate through the MSB even though they have an excellent unity gain buffer stage. When I am going to attenuate I would prefer my nonlinear steps be second harmonic...ergo the GAT or Ref 10.
As an aside, this review of the GAT used the Pass XA200.5 as one of the amps with great success.
Regarding point (2), of course mine was a relative point being made to distinguish between stated Max Currents of both amps for comparative purposes only (i.e., they are fairly similar). It was not meant to confuse instantaneous Max Current with operating load, FLA or otherwise.
Sorry about the confusion and thanks again for your help.