Nothing to say you can't swap whatever op amps you're using between the DAC and headphone sides. Rumor has it, you can run either socket without a chip, and likewise with the tube if you're not using the DAC side. Haven't tried it myself. Anyway, that's where those extra risers might come in handy. Set up both sockets, and swap away.
Like I mentioned, I did spread the sides out a bit on mine. That helped some, but sliding was still a problem. Next step was to round the corners of the back plate with a dremel ... that helped a LOT, and it's one of those, if you didn't do it, you'd never spot it, kinda things. Still a bit sticky, so I spread a bit of SilGlyde in the inside corners of the box. Now it slides on and off real nice. Only thing is, I do have to apply pressure to the sides to line up the bottom screws, but that's a small price to pay considering the alternative.
Heck, on those extensions ... stack em all in there and put a flashing light on the top to warn airplanes. <G>
Seriously though, minimum is enough. Don't want to build too much capacitance into the circuit.
And yes - I have tried the triple mica RCA ... those are the Command Series I might have mentioned earlier. No sir ... didn't like it. Sound stage was cramped, and it was a bit on the shrill side. Also, the bass wasn't as defined as what I'd gotten used to. Then again, I didn't really give it a chance to break in (important with NOS), and I'd just scored a 1956 JW series WE 2C51 that was looking for a home. I've also got the double plate Command Series - haven't even tried that yet ... Too many tubes, not enough time ...
Granted - I may have gotten a bit carried away, but I started looking and kept finding real deals. I swear, that's it!!
Probably. <G>
PS ... I like the glasses case - just cut a piece of fuzzy velcro and pinched that up into folds to separate the tubes, then stuck it in. Protects the tubes nicely and makes for easy swaps. If it helps any, I've got them arranged in preference order, left to right, rated "eh" to "wOw" ...
- 1969 RCA Command 2 mica - haven't tried it yet, so no opinion
- 1965 RCA Command 3 mica - already went over that
- 1983 GE 5 Star - The "upgrade" tube that came with the D1. Real decent, but a bit muddy in the mids.
- 1972 WE JW-3C51 - Very nice. Good solid bass & dynamic response, wide stage, great mids and tweets
- 1961 Tung-Sol 2C51 - Like the '72 WE, but mellower. Real nice for orchestral and jazz. Very strong vocals.
- 1956 WE JW-2C51 - My favorite so far. Combines the virtues of the '61 Tung-Sol and the '72 WE, but with a bunch more punch. Bass is VERY tight. Detail is amazing - I hear a LOT more individual instruments in orchestal pieces than with any other tube.
- 1959 Tesla 6CC42 (not pictured). New to me with just a few hours, so the verdict is still out. Supposed to be about the best in the series except for the Bendix 6385, which tends to be VERY expensive if you can find one. Every tube I got, plus another $50 on average ... I'll pass.
Probably ... <G>
* Worth mentioning ... the first three were a bit tiring as time went on. The last three, I could listen all night ... Once again, jury is still out on the Tesla, but I haven't reached screaming for the off switch yet ...