Member's recommendations for tube amplification

The thing about the Coincident amps is that they just don't make enough power. The speaker has an efficiency (we hope; if its a 4 ohm load the situation gets worse) of 94 db. 7-10 watts is simply not enough power, especially if you consider that with an SET, the ideal speaker for a given amp will be so efficient that there is never a demand for more than about 20% of full power.

If you break this rule, the SET will sound a lot more 'dynamic' than it has any business being, due to distortion generated that the ear uses as loudness cues. The thing is, once you know that is the case, its hard to listen to a setup like that and not be aware of the distortion. So reading this may have wrecked it for you.

In short, while the *idea* is attractive, in practice an SET won't work very well with this speaker although it may sound fine at low volumes.

David_Ten, if an OTL may be of interest I’d suggest that you check out the following listing here for a pair of Atma-Sphere M-60s:

https://www.audiogon.com/listings/tube-mk-3-3-2017-09-01-amplifiers

The seller is Duke of Audiokinesis, and based on the many outstanding posts he’s made here over the years I’d have total confidence both in him and in any advice he may have to offer as to their suitability for use with your Tekton Double Impacts. I presume, btw, that your DI, and the DIse you have recently ordered, are in the 4 ohm configuration that is usually chosen. If so, it may be best to use an OTL in conjunction with a pair of Zero autoformers, to boost the impedance seen by the amp.

You may also want to consider a used (and no longer manufactured) VAC Renaissance 30/30 or 70/70. The 30/30 utilizes a push-pull pair of 300B output tubes per channel and is rated at about 30 watts per channel. The 70/70 utilizes two pairs per channel in a push-pull parallel configuration, and is rated at about 70 watts per channel. Both should be findable in your price range, although the 70/70 would probably be close to the upper end of that range. I use the 70/70 in my system, with 6 ohm Daedalus Ulysses speakers that like the 4 ohm DI have a very flat impedance curve, and roughly comparable efficiency. I chose that amp because I wanted one that would provide a taste of the 300B magic but without the usual power limitations, given that I listen to a lot of classical symphonic recordings that have very wide dynamic range.

Both of the VAC Renaissance amps provide three output taps, btw, including taps that are designated as being suitable for use with 2 ohm speakers!

Finally, a minor point re Larryi’s post: Larry, I think your mention of "Brooks" should have said "Brook." Brooks was a relatively minor manufacturer of FM tuners which existed in the same ca. 1950s time frame as Lincoln Walsh’s Brook Electronics Company, to which I’m sure you were referring, and which as you know manufactured very highly regarded 2A3 and 300B-based amplifiers. Although I suspect that any Brook power amps which may be findable today would go for vastly more $ than the OP’s stated price range.

David, best of luck in your search.

-- Al

@atmosphere 

For what it's worth, I filter out 70Hz (-3db) and below (-12db @35hz) from the amps and speakers (using a pair of passive filters) and I am letting my ML Depth i subwoofer handle the bottom range; IMO, this has worked wonders in driving the Omega speakers with the Franks with substantially less distortion; I don't detect any distortion, but if there is, I have no objections to it :)

For what it's worth, I filter out 70Hz (-3db) and below (-12db @35hz) from the amps and speakers (using a pair of passive filters) and I am letting my ML Depth i subwoofer handle the bottom range; IMO, this has worked wonders in driving the Omega speakers with the Franks with substantially less distortion; I don't detect any distortion, but if there is, I have no objections to it :)

The point is that unless the amp is outright clipping, the ear does not detect the distortion as such- in almost all cases, the ear converts distortion into tonality. But because the ear also uses higher ordered harmonics as a loudness cue, if there are higher ordered harmonics in the signal, the ear will hear that as louder.

In an SET, the higher orders start to show up when the amp gets to about 20-25% of full power. Since music has most of the power in the transient leading edges, if the distortion is only showing up there it will come off as 'dynamic'. Lots of people like that (often though without understanding how its happening) but it certainly isn't natural!

If you really want to hear what an SET does right you need a speaker that is efficient enough that the 20-25% of full power is not exceeded.

 Also consider these Audio Note monoblock amps for sale; 
300b parallel SET monoblock amps. 

http://www.usaudiomart.com/details/649306274-audio-note-300b-parallel-legend/

Music Reference RM 10 would also be a sweet match with your DI speakers in my estimation.  Great little stereo amp that has proven itself as a winner for decades now.