Rotel Class-D Amps with Martin Logan?

If you remember my older posts about running a pair of Martin Logan vantages off my Onkyo receiver then you'll know this post has been long in coming...

Anyway, I'm looking for a good 2-channel or 5-channel outboard amp to replace the internal amps of my Onkyo 705 which has served me well but just doesn't live up to the potential of the ML Vantages.

My initial thought was to get a used Rotel, Adcom, Outlaw, or similar "budget" yet still high quality dedicated amplifier. In doing this research I uncovered a lot of rave reviews for the Rotel 1077 class-D 7-channel amplifier, and now more recently the 15-series. In particular, I'm most interested in the RMB-1565 5x100 watt class-d amp. A combination of great price, clean low-distortion sound, really good low-impedance handling, and a natural doubling of power from 8 to 4ohms (and again to 2ohms) seems to make this a great buy.

Here's what I'm wondering:
1. Is 200 watts (@ 4ohm) per channel enough to do the Vantages justice? Or do i need something more robust like the rmb-1575?

2. Has anyone else here used any of these new ICE-power class-D amps with your martin logans? How do they work with ESLs? (I've heard a few good reviews, but am always looking for more first-hand experience)

3. What are some other (or possibly better?) options around the same price range ($500 - $1500)? For example, are the Emotiva amps any good??

Thanks!

I'm driving my Clarity's with a 1560 AVR right now & do have the 1572. (moved two months ago and have yet to plug the 1572 back into the system) If you check out my system, my normal configuration is the 1572 driving the Clarity's and the AVR driving the centre & rears.

Anyway, the power from the AVR (100 wpc into 8 & 200 into 5), it not only drives them well but better than my old Rotel class a/b amp and the Parasound A21 I had from a while. The sound is very clean & smooth with good weight, great imaging & depth and pretty smooth across the entire frequency range. With the class a/b stuff I was getting a harshness in the mid-upper frequencies and this has totally disappeared.
The 1572 provides the same sound but with better dynamics. I purchased it mainly because I'll probably end up with Vista's and wanted some real punch to drive them. (also compared the equivalent Bryston and preferred the Rotel with the Vista's)

The Vantages have self powered woofers so they will probably be less demanding than the Clarity's. No need to worry there.

I think that going with the 1572 (2ch version) or 1575 (5ch version) is the better way to go just for the extra low end weight & dynamics.

Good luck with it!

I have been using Spectron amps, using one stereo configuration and a then a pair of stereo amp configured as monoblocks, 1 per channel with ReQuests and then for just over a week with CLX's. The Spectrons differ a bit from most class D amps as they have massive power supplies, which have been developed over the years by John Ulrich. My Musician II's also have the bybee and v-cap upgrades, which makes them a bit more refined. I also have a Plinius SA-250 Mk3, for direct comparison and that is a linear amp that can be run in either class A or class B mode, via a selector switch. On all configurations I use balanced iC's and I use Nuforce speaker cables (which BTW are amazing and have real science, not snakey oil in their design).

There is no doubt in my mind that whether it is class A, B, or D; the more power the better. A Spectron stereo amp does sound very nice, but when you double the power by bridging into monoblock mode the control and presence is noticeably enhanced. Similarly, the Plinius has so much current, it can handle any impedance curve swings and there is this effortless feeling and drive.

The Plinius wins over a stereo Spectron, because there is just a better sense of definition and control. The monoblock Spectrons though have gobs of air and are very dynamic and spread the music out. The Plinius is a tad more textured and centred and so I would not say then that the linear amp beats a class D topology.

There is no doubt that because the CLX's are so revealing that the Spectron's own clarity and dynamic character shine through and there is very much a "live" feeling to both vinyl and digital sources. In this configuration SACD demonstrates its superiority over redbook and HDCD and XRCD are also superior. For the record I use MAC G5 as a music server through Mhdt Havan tubed DAC via Toslink or Kora tubed DAC via Bel Canto USB link.

So all of that is a long way of saying that I personally have no issues or concerns that class D amps sound over bright, or fatiguing or brittle with ML's. In fact, if you like a "live" transparent character they might be the best bet. I have also heard Nuforce and Bel Canto amps at my dealer with Spires and they sounded very nice on digital with no issues about compatibility.

The best amps for ML's imho are those with lots of power headroom, able to handle impedance swings through good current delivery and dynamic headroom. The Spectron website gives a more detailed perspective that is worth a read.

Steve