Driving MBL 121: Accuphase or Gryphon

Desalvo,

You probably want to keep your Pass amps as they are very good. Try other speakers that are more efficient. The 121's although rated at 82 are actually more like high 70's.

Thanks for the various views expressed.

I had the opportunity to audition the MBL 121 side by side with Thiel CS3.7 powered successively by Pass Integrated 150.5 and Pass 250.5.
The X150.5 was a far cry from what it takes to move the MBL121 and was not convincing either with the Thiel (compressed, bright, aggressive, small sound stage). The X250.5 was a totally different story and was at ease with both speakers even though the combination with Thiel was not my cup of tea (again axcessive brigthness, highs a bit aggressive and not sounding enough organic: I am not sure if it is the amp or the speakers which are to blame most). By contrast, the 250.5 was a good match with the MBL121 which blossomed in comparison with what they could deliver powered by the 150.5. And the space that these tiny monitors can feel is simply incredible (and the limited bass range does not strike me as a pb in a normal home listening context).
In a nutshell, I agree that the MBL121 (and in general) need power to be moved and to deliver their staggerring soundstage and fantastic lushness but I really had the feeling that the X250.5 did not run out of steam with them. It should therefore be a piece of cake to pair MBL121 with the X350.5. More watts perhaps would not harm but I wonder if you really need 1.000w per channel. I am powereing a pair of MBL 116 with a Plinius SB301 (310w into 8ohms) which drives them seamlessly and, IMHO, effortlessly.

Cheers,

Fabrice

A lot of it depends on how hard you want to drive the 121's. At high SPL's, the 121's sound shrieky and congested, the soundstage collapses especially with orchestral music and opera, if driven with inadequate power. With the Plinius and X250.5, it is quite likely you are not driving the speakers too hard. If your listening levels are moderate, then these amps should be good enough for the 121's. But the 121's need to be cranked up to reach their full potential, for optimal soundstaging and airiness, midrange richness and instrumental bloom. Otherwise, they sound a bit dark.

I now have the 121's mated with the 350.5. Just an amazing soundstage. Very dynamic down to the 50Hz region. I feel you need a pair of subs with these. We have one so I get a bit of off channel balance.

With the Pass X350.5 no strain noted what-so-ever and completely at ease. I would expect that with a 150 lb amp.

Last night we watch a movie through the 121's. Note I have a single JL Audio Fathon F113 doing base duties (I'll add a second one later). OMFG. I didn't really realize or even think about these speakers in a HT context but they made me think of it! These speakers are more incredible than my line arrays and my line arrays are unbelievable in HT. I could see no reason to have surround sound with the MBL's IMHO. They seem to produce surround sound all by their little selves.

I use my MBL 111e's in an integrated Home theater/two channel music set up; and power them with the Bryston 28sst's monoblocks; much better dynamics and sound now with this extra power; then when I was using the MBL 8011's; which I thought underpowered the speakers...for theater; I use an Aerial CC5 center speaker; as I thought it would be difficult to get proper dialogue with an omni speaker for center channel duties; and it integrates great....sounds like you are on the right path; I have one Velodyne DD15 as a sub; but the MBL 111's have their own woofers; so I don't need as much extra base as you will.
Enjoy; and let us know how you solve these issues...