good preamp for dynaco mk3 monoblocks with maggies

I'd suggest you think about the Promethius Signature TVC that is for sale now. This is a superb passive- if you don't need gain. I don't think you can come close to this level of transparency for anything close to the price. Also, being a passive, it is just dead quiet. No relationship with the seller.
I used one of these in a Magnepan based system with good results, and although it is sitting on my living room floor unused right now (having been replaced with a $5.5 K Coincident), I'm holding it until I'm sure I won't have use for it in a second system.

Zvovchik, It looks like the Promethius statement that was listed must have sold. I owned and used the TVC4 for about 4 years prior to buying the statement. As far as comparing the TVC4 and Statement, I would say the top end is more extended and airy in the statement. Cymbals, woodwinds etc are much more natural. Also, I seem to recall better localization of instruments and certainly more air around the instruments. The TVC reference 4 is a very good piece, and an excellent value. The statement pretty much gives you a bit more of everything, but they are cut from the same cloth.

I also used the Signature with Monoblock amps, and yes, you have a separate volume control on each channel. The volume controls and input selectors are top notch.
The Promethius website does not list the price of the signature. Nicholas used to make these special order only for repeat customers, so I was a little surprised to see it show up there at all.

Zvovchik, You can plug a phono pre into one of the RCA inputs on any of the Promitheus TVCs.

Rcprince, thanks for the comparison with the Shindo. The Promithius Signatures are just a crazy good value proposition. Nicholas really needs to establish a US distributor and give them an inventory to work with. These things would sell like hot cakes at 3x the price with a bit more exposure and easier access.

Dover, It is always essential when considering use of a passive pre to consider both the amp and the sources. One must be very careful about system matching, although TVCs in some ways can be more forgiving than other passive designs.

In the 1K price range for preamps, there are necessarily going to be tradeoffs. The Promitheus TVCs can be a steal if the rest of the system lines up. I don't know the Dyanaco amps. The OP should consider your experience with those amps carefully.