Most transparent amp you've heard?

Tvad, I would still say Atma-sphere with the audiophile dictionary" definition. I can also see how in a sense Joule can be considered transparent, yet I would not say it is uncolored. I would also agree that the Pass XA.5 gear is very transparent in terms of being balanced across the spectrum and having a neutral timbre.

Drubin makes a good point. What I meant was low noise, speed, space between instruments, and a sense of immediacy.

Atma-sphere amps, hard to beat no transformer.

Well, I don't know about absolutes or anything, but one aspect of a transparent amp, or system, is that the soundscape changes signficantly from recording to recording - that is the system tends not to be homegenized in sound signature, but let's recordings come through more tellingly and reflecting the differences between recording venues and engineering - to me, that is usually a good sign.

When Ken Stevens of CAT was asked by a resistor manufacturer what kind of flavor he wanted, his answer was that he wanted them to have the flavor of water. I think he meant that the sound of a piece of equipment should be like a chameleon so that issues of bass, soundstaging, imaging, dynamics, etc are a refelection of the recording, not an overlay on the recording. I think this is he definition of neutrality and transparency. I think the CAT was very transparent in this sense, and to an even greater degree the Atma-sphere amps, at least with my Merlins.

Sean, do you need more than 6-12 watts for those speakers? Do you know what the impedance is like across the spectrum?

Sean, based on those specs, I think that JA is right and tubes amps are not the way to go. As transparent as the Atma-spheres are, they seem like less than an ideal match, even though some may chime in that you can make it work with a speltz transformer which would defeat the transparency rationale to some extent. IMHO, you need SS and in that camp, I think you could do a lot worse than auditioning the Pass XA.5 series (the best SS I have heard, but I'm a tube guy so take that with a grain of salt), I do think that XA-60.5s would be enough power for you - they have a lot more drive than their specs would suggests and they are by any definition transparent. Oh, and did I mention they are uber reliable? An alternative is to consider the X-Series which gives you more watts per $$$, but are not quite as good to my ears (but still excellent amps).

In my opinion, the tubes amps on your list that have the best chance of handling the load of your speakers are the CATs (I owned them) - they can drive most anything (the Atma-spheres might work,I own them, but less than ideal IMHO), but you will still proabably be best served with SS (I owned the XA.5s are they are truly great sounding SS amps). Another tube amp that is neutral and would be able to handle the load would be the Music Reference RM9 Special Edition which is able to increase output into dropping impedances and puts out 160-200 watts depending on the tubes you use; if you use the 4 ohm tap the wattage drops a bit.

Boy Pedrillo, I would love to hear a nice Blue Note album on that turntable of yours!!