Best tube mono blocks under $15,000?

Atma-sphere MA-1's should give you everything you need as well as heat your home. As with all amps speaker match is very important.

Power rating: 150 watts/channel into 8 ohms/145 watts into 4 ohms
Power bandwidth: 2 Hz - 75 kHz within .5 dB
Frequency Response: (1 watt): 1 Hz - 200 kHz within .5 dB (-3dB @ 1 Mhz)
Phase Shift: less than 1 degree @ 20 kHz
Power supply storage: 600 Joules/chassis
Output section rise time: 600V/micro-second

Power consumption: 500 watts/chassis
Tube compliment: 14 6AS7s and 4 6SN7s per channel
Input impedance: 100k/ohms single-ended; 200k balanced
Output impedance; 1 ohm
Signal-to-noise ratio -95 dB

The impedance curve of the V2 that is shown in "Chart 5" here indicates that its impedance is around 4 ohms in the mid-bass region, slightly higher in the deep bass and upper treble regions, and rises to around 10 ohms in the mid-range.

Which means that a tube amp having relatively high output impedance/low damping factor (such as the MA-1's, which are presently listed at the Atmasphere website as having an output impedance of 2.3 ohms) will produce a mid-range response that is more emphasized, and bass and treble responses that are less emphasized, than would result with a solid state amp having low output impedance/high damping factor (such as your MC501's).

The MC2301 has a damping factor of 15, corresponding to an output impedance of about 0.5 ohms. Relative to a solid state amp such as your MC501's (damping factor 100, output impedance 0.08 ohms), the MC2301's will emphasize the various parts of the spectrum in a similar direction as the Atmasphere's, but to a lesser degree.

I suspect that a pair of MC275's operated in parallel mono mode would have an output impedance close enough to that of a solid state amp that the resulting impedance interactions would be similar.

I have no idea which kind of response would be preferable to you, or with the speaker generally, but those are some factors to consider.

Regards,
-- Al

I highly recommend that you give the Octave MRE 130's a listen in that price range. You might be able to be find them at dealers for an introductory price as they are just now being carried.

http://www.stereophile.com/rmaf2010/dynaudio_-_wadia_-_octave/

I think you will have some tough decisions at that price point, that is why I suggest that you listen to a variety of amps before you splunk down that much money.

Oh, I also own MRE 130's and can speak of their merits driving B&W N800's with ease.

Ciao,
Audioquest4life

I auditioned the Manley Snappers with Jumbo Shrimp preamp in my system driving Montana EPS2 speakers. Although I have a few amps, my primaries in this system are MC501 and C2300. Listening mostly to vinyl through a very fine analog front end, I and an audiophile pal with excellent ears preferred the MC501 and C2300 combo. The Manleys are very nice, and I could live with them easily. But the overall listening experience, including bass foundation, midrange presence and detail, and musical coherence gave the nod to the Macs. We also found the Manleys to harden slightly under pressure in the upper mids with these speakers, which can be a little forward there anyway. I'll add as a caveat that the amps may not have been entirely broken in, though I'm not sure how much difference that would have made in my decision. I wanted to prefer them--the switch would have netted me a substantial pile of cash (this was before the big price increase)--but it just wasn't so for me. I should add that I own a Steelhead and a Stingray II, so I'm a Manley fan. But I'm not sure you'd find the Snappers to be a sonic upgrade from your current combo. YMMV.

Hi wrm57,
I used snappers with a shimp and was also unhappy with the results,flat,no detail,etc.
Then I tried them with a ARC LS26.
an amazing difference.I think the shimp was your weak link.