Tim,
It is hard to predict whether or not a low-powered SET will work for you -- it depends on your taste and priorities, how loud you need your system to play, the particular characteristics of the amp you audition/buy, etc.
I will hazard a guess that a SET amp is within the realm of possibility, but, whether that would be an optimal choice is harder to guess at. When one looks at numbers, most low powered SETs seem completely unsuitable for all but the most efficient commercial speakers. But, I think most people will be surprised at how low a wattage is needed for satisfying volume.
Sonicbeauty raises a very good point about SET amps, or for that matter, any truly worthwhile "improvement" to a system. As one improves quality, the volume level that one tends to listen at should go down as the listener will not be trying to compensate for lack of resolution or poor dynamics with higher volume.
While SET amps using higher power transmitter tubes (845 and 211) will make power much less of an issue, they tend to give up something in the way of performance to the much lower powered tube types, such as the 2a3 or 45. They tend to be more expensive, too, because of the need for a beefier power supply and high voltage wiring. If you can listen to both low and high power types to assess the tradeoffs.
Another consideration is that a SET amps that truly represent what this genre is capable of delivering tend to be quite expensive. While the circuitry may be simple, really good parts are required. In particular, SETs require transformers designed specifically for this use and really good single-ended transformers are very expensive to produce. When priced on a $ per watt basis, SETs seem even more pricey. But, with compatible equipment, the sound is quite special.
