Tube amp for planar speakers and SS pre

I'm currently horizontally bi-amping a pair of ML Prodigy speakers with two ARC VT100IIIs. I was originally thinking about using a D400II to vertically bi-amp and drive the bottom end, but the bass I get is pretty tight as it stands...

I'm driving Magnepan 3.6's with a McIntosh 2102 tube amplifier and getting results results that I like a lot.

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Magneplanars and SoundLabs are both panel speakers, but different types - Maggies, as their name suggests, are planar magnetics, while SL's are electrostatics. (If you are unsure what the preceeding exactly means, yes there are previous threads to search on this topic.)

Anyway, what this implies for amp selection (beyond the normal fact that different speakers will of course sound different from one another, and therefore will potentially have different system matching requirements from a sonic standpoint, including amplifiers) is that the speakers' electrical properties are not the same: Planar magnetics show a very flat, resistive load, while electrostatics present a capacitive load that slopes downward to very low values with increasing frequency. So without going overboard here, the two speaker types make different demands on a partnering amp, which might not be met best by the same design for both kinds of speakers.

Having said that, what is generally true of all panel speakers is that they are only moderately efficient, so whatever type of amp is used, it can't be really low-powered if you want to play at near-realistic volumes in any but the smallest rooms (and panel speakers don't work well in small rooms anyway, due to their dipolar radiation pattern, so some power will be needed).

As for tube amps, a common pairing with electrostats is OTL (output transformer-less) amps, partly because they can put out increasing power with increasing speaker impedance, something 'stats exhibit where the power is needed - in the bass range. Whatever amp is used with a 'stat will have to be stable into a highly capacitive load through the treble. Maggies, with their lower impedance in the bass range, are usually paired with output transformer-coupled designs if going the tube route, but amp instability should never be a problem with their purely resistive load. A lot of folks feel that it takes a very high-powered tube amp, however, to compete with SS when it comes to supplying Maggies with sufficient current to really bring them to life (electrostats are primarily voltage-driven, making them more compatible with medium-powered tube amps).

These are just generalizations though, and other combinations are possible. While I lack the experience to make specific recommendations, you might want to bring your question to the attention of member Audiokinesis if he doesn't find your thread on his own.

Judit, if you listen to classical music as much as I do you'll want to look at my "Midrange Electrostic System" under my moniker ivanj. The big advantage you have over me is you have the Pass X-1; presently I have to settle for the Pass-designed Adcom. Seriously, the Wolcotts are a final purchase for either the Mags or the SLs.

I think you are getting good advise regarding final speaker selection. I believe your preamp might sound best from it's balanced outputs. I'm not sure how critical this is in the big picture, but you might want to consider maximizing the sound of the units you already own and seem to be working around. You may find it challanging to find a tube amp that meets all your requirements and also has true balanced inputs. Good luck.