Which speakers will fill 5,000 cubic ft coherently

Swampwalker-

Yes...The MC 352 does use output autoformers.

To quote McIntosh...
"Output autoformers, a feature of many of our amplifiers, assures that you get all the power you paid for. Other amplifiers, optimized for 8-ohm speakers, have warnings not to use with many speakers that are 4 or even 2-ohm impedance. Others are optimized to work with these low impedance speakers, but deliver only a fraction of their potential power with 8-ohm speakers. Output autoformers avoid this problem, with separate connections for all three popular speaker types, insuring full power, without stress, into any speaker regardless of impedance."

Unless I miss my guess, the output autoformers are essentially the same thing as using the speltz autoformers (which have different impedence multiplying taps), except that they are internal to the amp. So we are still back to the same issue; most tube amps (and esp. OTL amps) prefer/sound better with a high impedence load. However, (and here I may be wrong) the large # of output tubes in the bigger Atma and Joule amps, make them a better match for a lower (not low) impedence speaker (assuming a flat impedence curve) than might otherwise be expected.

Swampwalker-
As far as the Woodmeres go..If Ty says that they would work fine with an OTL amp..then you can take him at his word.

He's never steered me wrong.

BTW..if you go with Tyler..I guarantee you will not be disappointed with not only with the sound of the Woodmeres, but thier more than obvious craftmanship, too.

Just a fantastic speaker,imo

>>03-18-08: Mustagefan
The perfect speaker for is the LS9 by AV123 it is 8ohm.<<

I just spoke to AV123. It hasn't even been assembled yet, although the GR Research model is available in kit form. So, not exactly ready to buy!!

I think some people are stretching the point about tube amps not working well with sub-8 ohm loads. As a rule OTL designs prefer high impedance loads, but tube amps as a whole can work perfectly well into lower impedance speakers. If you take into account the output impedance of the amplifier you'll find that most tube amps work best with speakers that have smooth impedance responses. But that is also the case with most transistor based amps. With the proliferation of single end triode type amps, which as a group don't do low impedances, all tube amps are being unfairly tainted as incapable of driving real world speakers. Any number of Audio Research, Conrad Johnson, VTL, Manley, EAR, etc. amps thrive on driving low impedance speakers.