Best high current high power $5k amp for MBL 121

I've narrowed down my choice of amp(s) to the following to help me drive my MBL 121. The speakers are very inefficient at 82db and with a 4ohm load. I can consider amps for around $5k used but would like to spend a lot less if I can. Amps include:

Spectron Musician III SE Mkii
Plinius SA 250mkiv or 301
Pass Labs 250.5 or 350.5
Cary 500MB
McCormack DNA 500
Bryston 7BSST

I welcome any suggestions, especially from folks familiar with driving these speakers, and also welcome thoughts other amplifier options.

I play a wide range of music and varying volume. I'm typically a tube guy, and I value liquidity, airiness and naturalness above all else. I find I care little for pursuit of a low noise floor at the expense of other aspects of music reproduction. I find I don't particularly mind a sound that some may find colored if it breathes life to the music (I have a Supratek Syrah preamp that I love). I've had one or two highly regarded amps that may be considered accurate or transparenet, but which I found to be dead and lifeless.

Anyways, I welcome advice and input on what is an expensive purchase for me that I want to get right. I may also consider a far cheaper amp (a giant-killer, if there is one) that may not get me all the way there, but which will make do for a year or so as a good bridge to a better amp later on.

Finally, might there be a tube amp option for me? Again, I need a high power solution, and even moreso, I need a high current solution - to drive these speakers properly.

The only tube amps I am aware of that can drive mbl's are the CAT amps (the original JL-1 was allegedly specifically built to drive the 101E). They are finicky, however, and require someone with patience and money.

Not to be a pessimist, but I wish you luck, as most high-powered amps sound artificial due to all of the output devices. The original Classe Omega is actually pretty listenable, but at 250 lbs., a pain to install and deal with.
Seeing that you mention a preference for tube's; you might want to add Wolcott P220 mono's to your list. Although I have no experience with MBL. the Wolcott's are exceptional and high current, power. I have seen them used in the $5-6k region. (You have a nice list of SS amps though)
If you have preference for tubes and I presume life-like sound then you simply have no choice among amplifiers you listed - Spectron Musician III SE Mk2. Its laso much better (sonically) then CAT and VTL high powered amplifiers.

All The Best
Thanks guys for the suggestions so far. The CAT would be to pricey for me alas, the Wolcott is an interesting idea I'll take a look at. Dob, I confess the spectron was at the top of my list - it's the one I'm leaning towards.

Another amp I thought of was a Moscode 401r - a hybrid design, and one where I could add a second amp later for mono configuration. Still though, perhaps the Spectron is the best bet. I'll need to keep an eye out for the right price used though, as it is beyond my budget anywhere close to the new price..
Hi Outlier, I am extremely fond of the Spectron Mus 3 amp for its musicality, cleanliness of sound, and authority. In the same $5K range you may also want to have a good look at the Nuforce Reference 9 V2 SE monos which I also enjoy, although I have not been able to compare it directly with the Spectron. besides these devices sounding extremely good, they run very cool to the touch as their power conversion efficiency is over 90%. . . and having 'green' amps in times of soaring energy costs is not bad a thing at all at all at all! G. Just remember that there is no such thing as an absolute 'best'. . . there is only what you prefer. . . with your own ears, for the music you enjoy, in your own system. . . for the reasons that are important to you.
Hello Outlier,

Please be careful with Moscode 401. A few years ago, it was reviewed in Stereophile but John Atkinson noted that this amp will not be able to handle loads below 2 Ohms. to my surpise, the designer, in Manufacturer Respond section, agree.

While, very musical and involving this amp is not for your speakers. If you think about monoblocks then its probably even worse, since bridged monoblock sees only half the load.

Guido - I wonder very much if you have examined NuForce in speakers which are extremely difficult to drive?
As I recall, in TAS Nov 2006 issue - this amp was praised immensely by some reviewers and cursed by others.
So your experience would be of immense value.

Thank you in advance
My preference is for natural sound as well. Pass Labs X250.5 that I own for 2 years now fits the bill. I listen to a wide range of music, anything from Metallica to Mahler. The Pass has no problems driving my B&Ws, although they're more efficient than the MBLs. I doubt Pass would have any issues driving the MBLs. I looked at your system and you have very nice components. Another thing with Pass amp is that it is very transparent and lets you hear what each component before it is doing. I recently tried 3 preamplifiers in my system, and each time Pass revealed their strengths and weaknesses. It's a great amp.

Good luck with your search.
Hi Guys:
Thanks again for the input. I used to own the older model Nuforce 9.02 monos, and I sold them within a week of receiving them, as they were comfortably bettered by the KR amps I had at the time - very different amps, and I was using them with a previous set of speakers - Focal Diva Utopia Be. I'm sure the new/latest Nuforce are much better. I have a good friend who has the Nuforce 9 V2 SE amps and he may bring them by for a listen with my MBLs some time soon.

Another option I may consider is getting the Musical Fidelity Superchargers - that would give me the flexibility to use a lower power tube amp, while still delivering a lot of current, power and headroom for my MBLs. Still pricey though, and so perhaps the best bet is for me to run with the Spectron..I agree Guidocorona about the power issues too - it would be a treat to be able to keep the Spectron on permanently and draw so little power, compared to the more traditional linear solid state designs which can eat power even in standby mode.
High again Outlier, I have the impression that switching amps like NuForce, JRDG, Spectron, and likely many other class D amps take a very long time to break in and reach optimum performance. . . probably about 1,000 hours of making actual music. Make sure that any class D amp you audition has been fully broken in, before you do any critical listening. And even when they are well past breakin, they may require a few days of music making if they have remained turned off / disconnected for a significant spell. Patience is #1 with class D amplification. G.
Just to update - I pulled the trigger on a Spectron. It's just the regular Musician III, but I intend to pursue an upgrade to full SE mkii at some point in the future. I haven't received it yet, but should have it in a week or so. Can't wait to power up my little MBLs.