Did you use your Light speed preamp with the Krells? Seems like it would be a suitable match .
No Charles. The Krells were long gone before the Lightspeed.
When it comes to impedance matching, sometimes theory <> practice. ie: On paper, McIntosh C2200 is a good match but was horrible with FBP600. No bass, highs, dynamics ... just lifeless!
I did try Lightspeed with TRL Samson monos. Samson input impedance 69K, 1M ASI Liveline IC, MW Transporter so excellent match but I didn't like the sound compare to my active.
To be fair, a MP of 60's Siemens Cca or 60's Tele e88cc in my active is more expensive but overall sound quality is more important than value to me.