Does anyone have any suggestions for duets for male voices, e.g. bass and tenor, that are relatively accessible and don't need keyboard accompaniment? Am looking for duets to sing at home with OH, you see... Thanks!

How about some Purcell? There are some to be had on Schubertline and you can alter the keys to suit.

Unaccompanied? That narrows it down a bit, what about Morley? I'm sure he has some unaccompanied duets (I think I have an arrangement of them somewhere as recorder duets)

If you have a trusty Yammy you could record an accomp. of course and then sing along.

Does it need to be classical ? If so the Pearl Fishers' duet is lovely, nice harmony etc - but the first part will sound odd unaccompanied.

If not, try some good showtunes - Live with Somebody you Love from Martin Guerre is great (although more for light baritone and tenor)