Buy a secondhand pair of McIntosh 275's and parallel the outputs of each amp. This will give you 150 watts per side - only a 3db difference from 300 watts!
300w tube amp monos - which one?
There are several highly regarded tube amp manufacturers, and pricing is comparable:
Audio research, vac, mcintosh, Conrad Johnson, etc
Basically, each mono uses either 8 kt88, or 4 kt150 tubes.
How does one decide which one to pick? Any recommendations or experience comparing these amps?