Lean sound. What's the cause?

Any of your choices would help to eliminate the 'leanness' of the MAP1. I have owned the CJ Premier 16LS2, VAC Renassiance mk II, BAT VK-31/50/51SE, but I have not heard a more modern VTL preamp. These are all very different, IMHO, but all would help negate the 'leanness' that you now hear. The CJ is rich, warm, sweet, but not very dynamic. The BAT is warm and dynamic, but not really sweet (compared to CJ and VAC, but sweeter than McCormack).
The VAC Renassiance mk II, and the Standard preamp are more extended and airy in the high's than either the BAT or the CJ. The VAC is also sweet in the midrange, yet does not have the power or authority in the bass that the BAT has.

So you have some decisions to make. Yes, all of these choices will eliminate the 'leanness' of your MAP-1, but do you also want more power and slam? (BAT), The sweetest midrange? (CJ), or the most extended, airest high's? (VAC).

You pays your money.....you makes your choices. FWIW, I've often been drawn to mostly VAC and BAT gear. Though I've owned mostly BAT gear, I'm currently living very happily with VAC gear.

Cheers,
John

BAT sounds closer to solid state than tube, it could sound lean with the ML335 also. I suggest you look into Audio Research SP-16 or LS-25 (the original, not MK2), either one will be good match for the 335.

Coincidence ! I've tried in my system many preamps a few months ago. Calypso, VTL 5.5, ARC 17LS. Ended up with a VAC Standard LE because availability of one unit in mint condition at a bargtain price near my location. A little bright, forward playing and very dynamic unit. With tube rolling, got it to play to my tune. Replaced it by a Premier 16 LS2 recently only because of the ridiculous price I paid for the latter. You're dead on about its signature though, so I still keep the VAC in case of. But.......

In all the trials I have done, the one unit that impressed me the most for its overall qualities is the VTL 5.5. A very nice mix of warmth and dynamics. Its like listening to a CJ with more punch. I wondered if it is because of the double mono configuration. Could enjoy my soft jazz as much as rock on this thing. I tested it for about six hours in two listening periods. The pleasure of trying several albums on it made me forget to assess its soundstage quality though.

Unless one spends BIG bucks on a multichannel receiver, these things necessarily compromise sound quality. In particular, volume controls are critical to sound quality and good ones cost a lot of money. So, most multichannel receivers go with cheap attenuators because that one component would otherwise swallow up a big proportion of the parts budget.

It's hard to guess how lean any particular component will sound in any particular system, much less, what "lean" means to you. Typically for me, it is not that cheaper solid state is tonally lean (weaker in midbass) as such gear tends to sound brittle, harmonically bleached (instrumental color, overtones seem stripped away) and mechanical sounding. Better solid state gear that avoid these problems tend to be a touch polite and dull (e.g., my friend's Hovland linestage, my Levinson Ref. No. 32). I also have a Placette Active linestage which I actually think is pretty good sounding, though just a touch hard sounding. Amoung solid stage gear, I generally like the sound of Ayre gear.

I currently run a tube linestage (Emotive Audio Epifania). I generally prefer the sound of tube gear myself. But, there is no easy way to characterize the sound of tube gear, particularly since tube linestages are MUCH more unpredictable in how they match up with other gear. The spectrum can be quite wide -- from extremely lean (e.g., most Audio Research gear) to extremely warm (e.g., Cary SL98). It's hard to say what you would like and what would work in your system. Personally, I've heard good tube linestages from VAC, Joule Electra, Shindo, Kondo, Audionote (uk), and VTL.

Thanks for all the comments. What I mean by the "lean" sound is in the comparative sense, not in the absolute sense. Unidisk SC has a built in volume control, so I can bypass the preamp and compare the results. I thought it sounded leaner with the preamp in the chain than without. MAP-1 sounds pretty neutral otherwise, and it doesn't add or take away much in the sound.