Audio Electronic Supply SE-1....

I use an SE-1 with Merlin VSM-Ms (91dB/w). Sophia 300b tubes make this a great inexpensive amp.

It will be 7W with 300B tubes. For 5W (2A3 tube?) you could get about 96-97 dB (90+6,7) with 90 dB at 8 ohm/1 W rating. I even used it to drive Maggies (83 dB) at good result (not very lound though)

Ake

Yes, if the speaker has a reasonably easy load. Like around 8 ohms with no wild impedance swings. It will actually play louder than you might expect. It won't "blow the house down" but it may be stronger than you'd imagine, for only 5 watts. Of course higher efficiency speakers would help out to make it play even louder.