VAC amps-grainy ?

The VAC is a very good sounding amp, and if you already have NOS tubes, I would look elsewhere for the problem. The Wavac amps are better than the VAC, as your dealer suggests. The real issue is whether something else in your audio chain needs improvement before investing in a Wavac. I have no experience with your DAC, but as a rule, I do not like passive controllers. I don't know how you plan to bypass the volume control function on your ddev 3.0. If possible, borrow before you buy, and don't rule out an active tube preamp as a possibility.

I have heard of no instances of VAC products, and yours specifically being grainy. A dealer will often denigrate a product, but trust yourself. If you like the sound, then you'll be happy. Even if he is being forthright, people have different tastes. Some people love chocolate, some vanilla. I know I'd be happy with your amp/speaker combination, but that's just me. As far as your DAC goes, I have no experience with this. But if the sound did bother me, I'd listen to a different one, just for comparison. And again, NEVER trust a dealer more than your own ears. They make no money if you're satisfied with your system. Talk is cheap, if he could put a bug in your head about your amp, if may open your wallet. All I know is that VAC makes great sounding stuff, and I don't even own any. Certainly, audition the passive preamp with an active one, if you're going to upgrade. Go with the one that feels(and more importantly, sounds) right to you.

Yes, I too feel the vac amps are somewhat hard. I have heard the 30/30 and it did sound hard.Also heard the 80/80 and it too was hard.I know this will upset vac owners but this has been my experience with vac. Possibly comes from their use of silver coated wire. In my experience this type of wire is always hard or grainy