Krell KSA 100s: Your Thoughts

Hi ps,

First, great preamp - I am a big fan of the MFA Lumi and Magus preamps.  As to your question, I had entry level Magnepans back when I was in law school (almost 20 years ago, now), and experimented with a number of solid state amps at the time.  I don't think solid state amps are "inherently" better with the baby Magnepans; rather, you simply need an amp that can deal with their relatively low sensitivity (as I recall, the MMGs are ~83db/2.83V/m), which does require an amp with some juice behind it.

As to the KSA100s, I would recommend you try before you buy, as the combination does not seem to me to be the best fit.  If you are wedded to the KSA series, I would actually recommend you consider the KSA-50s, which had the sweetest treble and the best overall balance of the line (from my recollection).  As to other solid state amps, I had good success with Jeff Rowland amps - you can get a pair of Model 3s under $2k, and I think they would make a nice combo with the Maggies.  Also, the Plinius SA-50 (mk ii or later) or SA-100 would be solid choices.  For amps of more recent vintage, the Odyssey Kismet is a nice amp, and can probably be found under $2k used.

One caveat, however: I am not sure of the output impedance of the MFA, but suspect it is on the higher side (you might want to check with Scott Frankland, who is the "F" of MFA).  As a result, you need an amp with a higher input impedance.  The Plinius amps had 100kOhm input impedances, and the Rowland Model 3 had a selectable input impedance with 100kOhm as the maximum, of which should work well.  Other solid state amps may be much lower, which could present problems with the MFA. (If you are wondering, the Krell KSAs were 47kOhms, which should also be OK).

With all that said, if it were my upgrade $, for the $2k I would go higher higher in the Maggie line, grab a pair of 3.6Rs and not think twice about it (two of these are on the 'gon right now for ~$2k) - they will give you much better bass extension and better dynamics than the MMGs, thereby potentially solving your issue.

Best of luck.

The KSA 50, while much less power, was the best sound Krell I've ever heard. To me it was much like a Mark Levison ML-2 on steroids. 
Either Krell will deliver more bass slam, and that can be impressive, but I don't think either would be more 'musical' than what you already have. I did big amps with slam for awhile, it gets old fast. Tone is where it's at for me.  Your current system I would imagine does 'tone' extremely well. 
You might also consider an old Mac amp. The MC-2300 will drive a half ohm load all day and put out something on the order of 600 watts per channel into it. Great sounding amp. I had one. 

Thank you all for your responses and perspectives- it's helped me sort out a number of things.

First, I'll assuredly keep the MFA mono amps and maybe have them taken to the "ultimate" level by Mr. Frankland.  He's already updated them once with excellent results.  He also updated the Lumi as far as possible, and when the preamp came back, it blew me away with how good it sounded.

Second, If I were to sell the MMG's and get into a 3.x series Maggie, I could bi-amp, using the MFA's for mids and treble, and a decent, moderately priced amp such as NAD.  Initially I was reluctant to consider 6' tall speakers in my relatively small listening room, but that's no longer an issue since it's a dedicated audio space. I will also audition the .7's as another alternative and forget biamping.  And, on the audio to do list for 2016, is room treatment, beyond the tube traps I already have in the front wall corners.

This seems to me, to be a much more logical approach- perhaps the best of all worlds for me given my taste in music and how it "should" sound.

Happy holidays to ya'll!