Masterpiece positioning

[Russr]

Regarding the hiss: The fact that the Masterpiece are active speakers (for bass) MIGHT be introducing some noise to the Lingdorf that was not previously a factor. Check if placing the speakers & the amp on separate power circuits helps. Also, did you ask the Lingdorf support folks if they have SPECIFIC reports regarding the 11s or 13s - if they just hear "Martin Logan" they might be referencing earlier (purely passive) designs.

If you like tinkering, you COULD buy second hand set of MLs (Prodigies, SL3's, even ReQuests), purchase replacement panels and any boards ML still has (Power, bias, etc.), and introduce an active crossover to drive the bass (with an affordable module amp like Crown, etc.). Will give you hours of "tinkering pleasure", cost a lost less, and sound pretty darn good! There are several threads on this forum describing members' work to do this for Prodigies, Aerius's, SL3's and I think ReQuests. NOTE: This is not some "inferior hack". Simply put, cost-effective digital crossovers were not in existence when the older generations were made.

 

[Kernel]

When I had my SMPS amps (Chord Pre, two Chord Monoblocks and a 5 channel Chord power amp together with a Classe' processor) all housed in one rack there was, indeed, noise initially when powering up the 5 channel amp. This eventually dissipated, at least audiably. Upon separation of the 5 channel amp and processor from the rest, there was no audible noise. All equipment was (and still is) powered from a dedicated 'HiFi only' ring main. I really like SMPS with the positives including a relatively small size and weight and NO transformer hum. The speakers I proudly own are ML 15A's.
It might be worth testing the system with the amp physically distanced from the rest.