Pass XA30.5 enough power for Wilson Sophia 2?

06-13-10: Keithr
Tvad- don't normal tube preamps have high output impedance...

By normal I'm assuming you mean tube preamps in general?

The answer is no. There are many tube preamp that have much flatter impedance measurements along the frequency spectrum than do the SLP-05 and Audio Valve Eclipse. See my list above for many that have this characteristic. In my list, the only one that varies considerably from the nominal output impedance is the ARC Ref 3. Check the Stereophile archives for more info.

Tvad,

Since you have a lot of experience with tube preamps, can I ask you what you like the best, and which ones have good bass?

So far I have been disappointed by all that I have tried, but other tab the two we already discussed, the only others I've tried is the Ref 5 and the Doshi Alep.

I might have to stick with solid state, but even there I've mostly had disappointments. My current ss pre is an H20 Fire, but I've had the
Parasound JC2, Pass XP 20, Esoteric C-03, and Wyred For Sound.

I dislike bloated, soft and inarticulate bass.

Thanks in advance.

These are the tube preamps that I have used with Pass Labs XA-.5 series amplifiers.

Lamm L2 Reference - 130 ohms
Lamm LL2 Deluxe - 250 ohms
Atma-Sphere MP1 - 30 ohms
SMc Audio VRE-1 - 250 ohms
ARC Ref 3 - 600 ohms

Of these, the preamps with the bass that I liked best were the Lamm L2 Reference, VRE-1, Lamm LL2 Deluxe and Atma-Sphere MP-1. The L2 had the deepest, crispest bass with excellent tonal balance. The VRE-1 is very close, but the bass isn't quite as punchy. The LL2 Deluxe's bass went very deep and had good clarity, but it was just a bit looser than the L2 Reference or VRE-1. The Atma-Sphere MP-1 went very deep and was nicely punchy and defined. In my system, for whatever reason, Atma-Sphere bass has been just a bit too pronounced for my taste.

They all matched well with the Pass Labs amps. Which you would like is completely a matter of personal preference.