Sub for 2 channel music only setup

Dlcockrum,
I feel the same as you about the benefits of a sub in the system. There is more overall body and fullness to the music and I think all subs load the room.
The SW-12 is forward firing instaead of downward like the Rel. I think that this helps with the issue of my seat vibration and the quickness I hear from the SW-12. I would think the presure of the downward firing to the floor has to reflect back to to sub and could cause the driver to move longer than it should. This could also be why you like it better with spikes, it sit higher off the floor and also make better contact. When I purchased my SW-12 Rel did not have the new front firing sub as they do now BTW other wise I would have tried one at the fime.

I had 2 Rel Stadium III for my HT slash 2 channel system. I felt the Stadium III was not fast enough and went too low for my 2 channel. I do not like subsonics when I listen to music. I sold 1 of my Stadium III after tring an Aerial SW-12. The SW-12 is much faster. It has an EQ, a left and right balanced input amoung other inputs and adjustments.
I connect the right balanced input from my 2 channel system and turn on the EQ so I can set it up just the way I want it. I want the sub to be there but not over powering. Then when I use it for HT, I turn off the EQ via remote (a macro)so I get full range from my 2 channel input and then a LFE signal from my HT processor to the left balance input for all movie effects. I took a while to get it where I liked it but it was worth it.
This setup has made me so happy I am going to get another SW-12 and have 2 subs in the front. BTW the Rel sub I still have is used in the rear.
For me I feel the faster the better when it comes to a sub for 2 channal, not how low it will go. How low do you really need a sub to go for music, maybe 25 HZ.

Dlcockrum
Yes I use the hi level input with a custom made connector and the same for the power cord. The only stock cable I do use came with my Shunyata hydra 6 power conditioner. My power cables are either FMS or Shunyata. Do not get me wrong I feel Rel is a very good sub, just for 2 channel I think it is not fast enough and it go's too low. I myself do not like my chair vibrating while I listen to music. For movies that another matter and if my room could support the space for 3 subs in the front I would have kept the other Rel.