My Ear 40 watt 834 is great.Know the sound of tubes.6550's are decent and cheap but EL34's will give better mnids.KT88's will give more articulate dynamics and bass but cost when you have to replace them.You can choose anything from a Jolida on up and tweak the sound with NOS be they expensive German telefuken 12AX7's (or other model) or cheaper Mazda's etc.Your output tubes will be too pricey to get New Old Sock but you can have fun with longer lasting cheaper driver tubes.Your speakers should be at least 89 db though generally you can double the power of tube rating versus solid state because thy don't clip as hard i.e distortion comes on slower.And of course more you can spend more options you'll have.
Chazz
Chazz