I own the M3 Sapphires and once broken in they sound great, but if you own a tube amp make sure you use the 4-ohm outs, as well as SS McIntosh with the Autotransformers. They go from very good to outstanding, the only thing to remember you will have to raise the volume on the preamp more, and what nice about that you will have more control over the volume setting due to this speaker being very effishent. My Mcintosh amp on 8-ohm has 29db of gain on the 4 ohms setting it drops down to 27db, on 2 ohms even lower 26 dB if I recall. What great about Clayton's designs is that he really understands OB speakers and all the drivers are made to work in an OB design. Many who say no bass, is from the past when boxed woofers were being used in an OB design they just did not work well. The Dalquist DQ 10 was an open baffle design except for the woofer which was sealed boxed, that open baffle midrange and highs were why so many people purchased that speaker, it sounded more open than boxed speakers of its day, natural to the music. Spatial Audio is light years ahead of that speaker and past OB designs, so don't knock them till you hear them, as a side note the bass shakes my room when it is there in the recording, except now with detail, texture, and nuance.