As with all tube gear with a transformer output the transformer is really important. EICO wound some excellent sounding ones. you also need to remember that in the 60s tube audio was state of the art so circuits and components were pretty much dialed in. So, with the plethora of tube units available at the time your dollar would buy better chassis or cosmetics or assembly. Fisher, I feel , was the leader in lower power units with 6bq5 and 7591 and 7868 output tubes. HH Scott also had some excellent sounding 6bq5 and 7591 amps but i am not so fond of the scott since the chassis is small and components and wiring is really tight. When you have a problem it can be challenging doing repairs. Next are the eico, heathkit , allied , knight , lafayette, sherwood, etc... I have listened to almost all of these and they are all amazingly good sounding if in good working condition. Which, is the problem,since you are dealing with equipment that is over 40 years old if the unit was sitting around for over 5 years without being used then there could be problems and you need to expect that and unless you are willing to do a rebuild yourself you need to budget for a rebuild.
But, in the end your 400.00 little amp will kill any solid state unit over 1000.00 and sound the same or better than any amp around 1500.00.
BTW, i have rebuilt eico hf 12 (3), st 70 (3 of them), 4 fishers and 3 scotts, lafayette, etc... and Eico is one of my favorites because. large chassis, point to point wiring, excellent component layout, conservative operating conditions, excellent sounding circuits, and superb sounding transformers. I am rebuilding 2 eico hf 32 which are like hf12 on steroids! they use 4 el84 in push pull parallel for 32 watts of real power. the transformers are huge bigger than dynaco st70. These units sound sweet with bass that you can feel. Big fat thumping bass. I have just finished rebuilding the power supply and will be putting them up for sale. Contact me if you are interested. thankyou, PRIMOTUBES
