there's the obvious ones, and the ones that will actually sound great with 481(3). eaa psp2 used (600), and ad500e or 1000, nowadays, you can come in under 1000 and maybe even get a 12v and breakout. And Paul Plotnik is fixing them. Sick, sick sick. Imo 480's, like 4022's, really need transformers to sound good, since they are so flat.