If you can break with the original thought of buying new, you might also be swung towards the push-pull camp - single ended is for hifi imho. Push-pull has power stage compression, crossover distortion and will sound much more like a big amp. You will probably not pay more for your 15W PP amp than a 4-8W SE (forget 10 single ended, you don't want to pay for those tubes). If you don't like to make too much noise while pushing the power stage, just go to a 10" speaker and you will get the same sound pressure level, with the added bonus of getting more speaker distortion as well (again sounding more like a big amp).
I have been looking at designing a mini-PP amp with just 4 tubes:
- 5Y3 tube recto for not having a standby switch and getting more sag;
- 12AX7 based preamp section for ease of copying existing designs and for tube rolling;
- 2x ECF80 or 80x or 82 which is a triode close to a 12AT7 PLUS a penthode close to an EL84, these will make an excellent point-to-point phase splitter plus power stage
...and I still think it would suit the purposes of someone like yourselves.
Think this size:
