NOS Tubes make a Huge difference

No I was not saying tubes don't make a difference at the output level. I meant to say that NOS were less important there, but I must admit I have experience only with 45s, 2A3s, and 300Bs. For all of these directly heated triodes, new production tubes are superior to all NOS tubes, including the old WE 300Bs and the Cunningham globe 45s, and single plate 2A3s. I should add YMMV.

RE: EL34 output tubes, I did get a matched quad of Electro Harmonix EL34s to swap out, and compare to the Svetlana's that came from VTL...

The EH EL34s sounded more detailed, but also constricted and kind of sterile. I just didn't have the same expansion of sound that I get with the Svetlana's. The Svet's may be less detailed, but when I have them in, that's not what I'm thinking... I'm thinking, "Woah, that's nice!"

The Svet EL34''s are nice tubes - stick with them; matched Mullards will be an expensive road. Its hard for me to believe someone can't hear the difference between a WE300B and, say, a Golden Dragon or Sovtek or...Some Mullard tubes sound mushy, rolled, etc., some don't. Any gas leaks don't help. I've liked the Mullard 12AU7 iterations, but thought other Mullard inputs sounded, as some have said, veiled. Go with twl's recommendation on the 12AT7's; he's right about the Phillips (upper mid glare, strident highs). As for your 70/70 purchase, its a push-pull single ended design (hence, your 70 or so watts) tubed on the outputs with Golden Dragon 300B in stock unit. Because VAC is the distributor for Golden Dragon (GD) this is understandable, and, although the unit is designed around the GD deficiencies, you can do much better than the GD in that amp. I can't remember if it has individual tube biasing, but I think it relies on close matching instead. Again, this is understandable given that VAC controls the GD tube, but if you want to do better, the expense of purchasing 8 (four per side?) matched new production WE300B's becomes, at $2000 ($495 per matched pair on audiogon new, assuming you can then match that pair to the others...), um, problematic. So, no WE300B in 70/70 unless you own an oil well. That's a limitation. Do look into other 300B iterations instead of the GD though (does Svet have their act together on one yet, or did they dump that idea?). But, because of expense, ask around with guys like twl before 300B re-tubing. Get a good amp stand or isolation platform also for the 70/70.

Dennis, I'd be interested to read your thoughts on the difference you hear with your new amp, once you get it and have had some time to compare. I think the VTL is quite a good sounding amp, but I've never heard the VAC. (Agree about the superiority of the Svetlana EL-34's).

Believe me, I'm just as interested in you Zaikesman in hearing what the difference will be with the VAC... I'm wondering if I'm going to think it was worth it. I mean, part of the idea of getting the VAC was also so I could then play around with different preamps (ordered a Supratek)... so we'll see. It'll be fun to hear the changes.

Asa... in anticipation of the VAC arrival, I've gone ahead and gotten some tubes to switch out on the VAC. Checking through some threads on AudioAsylum, most VAC 30/30 and 70/70 owners like the JJ 300bs. Some liked the Western. Most agreed that the JJs and the Western were the best sounding 300b in that amp. I found some JJs for $660 for matched octet. And I went ahead and got a couple of NOS 6SN7 (Sylvania VT231, RCA 6SN7GT, GE 6SN7GTB, and the ElectroHarmonix... )... so it should be a fun couple of days coming up! I'll post my impressions...