I'm running Atma-Sphere M60MkIII OTLs with Avantgarde Duo Omegas 108 dB sensitive horns. At first I did have noise issues to deal with, but due to my own fault. A terrible hum that I had never heard before with 92 dB sensitive speakers. I had a ground lifted that needed to be put back in place and that solved the problem. If you have a noisey tube in the gain section of the amp you will definitely hear it. The M60s use 2 gain tubes, for high sensitivity horns you remove the second gain tube and insert a shorting plug to reduce gain. The S30s only have one gain tube and I belive were designed with higher sensitivity speakers in mind. I also use Atma-Sphere's MP3 pre amp. With my ear to the mid horn I have to strain to hear any noise and the treble horn emits a barely audible fuzz. There is something to be said for minimum or no crossover designs used with an OTL. If you search the member systems, there is another member using M60s with DUOs.
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