Quote Originally Posted by Sir Terrence the Terrible
My amps have a high damping factor in the Low bass. I am not experienced enough in speaker building to fully explain how transmission line subs work. All that I know is that I can see with a accelerometer that my drivers exibit little to no overhang after the signal stops. The designer of my subs and main speakers (or redesigner if you will) specifically recommends amps with a high damping factor in the LF to enhance the performance of his sub designs.
No doubt that conventional dynamic woofers benefit from a low source impedance amp. Actually, the Onkyo M-501s have only fairly moderate damping factor (df=60 according to their website) which is a good indication that they didn't go overboard with NFB. As opposed to the horrible sounding pro amps with DFs in the thousands.

Quote Originally Posted by Sir Terrence the Terrible
My listening test with tube amps(regardless of price), and the subs in my mains shows that the bass is flabby, ill defined, and not controlled when compared to my regular amps. That is why I have chosen SS amps over tube amps for my setup. Bass is the foudation of music, if it is not well done, then it doesn't matter if the mids are sweet.
Beginning with your speaker of choice and finding a suitable amp is the way I went as well. Our outcomes are different due to the nature of our speaker choices and likely, our musical tastes. My preferences do not rule out tube amps as did yours. My amps possess a multi-layered dimensional magic with voices, woodwinds, brass, and percussion I just do not hear with comparable SS designs.

Vive la difference!

rw