Speaker Level and LFE Sub?

I need a sub that can combine the high level signal from the output of my 2 channel amp with the LFE of my surround preamplifier. I have a REL B3 right now which can accomplish this task. However, I am not totally happy with REL. I have an NAD M2 amp and the REL doesn't do great with the high level connection. I tried using the REL cable made for digital amps with no significantly different results. The NAD M2 doesn't have a line out for sub. :(

The G928, REL and Thiel's SS1, SS2 etc with the smartsub integrator are the only 3 sub manufacturers I can find that can run speaker level and lfe contemporaneously. Any other subs that can do this? Any external sub eq or dsp that can run both inputs at the same time?
Definitive Technology Supercubes, the whole line. Pull up their website and check out the manuals. A Supercube II should replace your Rel.

I have a Rel B1, that I am very happy with, but I am going to replace it with 2 SuperCube 1's. Really just to try something new.

Good luck.
Yep, I second the Def Tech recommendation as I am running a Supercube II in exactly the same way as you are describing.Fantastic small footprint sub with built in 1250 watt class D amp that offers excellent nuance for music and plenty of thunder for home theater as long as your room is not too large. If you have a big room there is always the Supercube I or the Supercube Reference. Prices especially used are very reasonable.
I read the manual. I can see that the super cube take speaker level inputs, but nothing in the manual says that the sub can safely take both LFE and high level at the same time. Are you doing this with a supercube? I just wouldn't try it unless the manufacturer has tested it to make sure grounding problems aren't going to destroyed my amp. BTW, most subs that take high level connections cannot do both high level and low level at the same time. REL is one of the few exceptions.
Sorry. Maybe i jumped the gun. I read this on their website:
"Both speaker level and low-level inputs are provided as well as a separate direct-in LFE low-level input (which bypasses the crossover network) which may be used by itself or in combination with left and right channel high- or low-level inputs for the ultimate in subwoofer flexibility and performance."

Velodyne SMS-1?
I called velodyne regarding their DD series subs a few days ago. Rob said that their subs do take speaker level but not at same time as LFE. The SRS looks like the same eq as in their dd subs and I can't find anything in the manual that says it can do this. Maybe I just need 2 subs.
Can I ask why? Is the NAD in a separate 2 channel system or are you using it as the front L/R amp in a combined system? If the former, you do not need simultaneous use of line and speaker level inputs. If the latter, the LFE/sub output of the processor will handle it all at line level.

Its a combined system. (NAD M2 for 2 channel via AES/EBU & Parasound P7 surround preamp outputing the .1 to the same sub and the left and right surround to NAD M2 via interconnect) So, technically I don't really need simultaneous use of line and speaker level inputs. However, if the manufacturer won't certify this particular use, I could destroy my amp with conflicting grounding. That is, i would have a connection coming from the NAD and different connection coming from a surround preamp. Also, I don't know how the sub would handle two inputs coming in at the same time. So, you are correct that I don't need to listen to line and speaker level at the same time, but its going to happen anyway when I am using the NAD M2 for my surround fronts and my preamp is sending LFE at the same time.
Yo Big D, or as we in Houston like to call Dallas, that little city in South Oklahoma, I am going to do the exact same thing that you are, that's how I discovered the Def Tech's could handle that.

I suggest you do as I did, and call the very nice folks at Def Tech and ask them about it. They were great to work with and described in detail how this would work, and said it would be no problem at all.

Good luck.
I really doubt there is a grounding problem here but I suggest you contact NAD since the M2 is the only strange item in this setup. None of the other items will be a problem.

Thanks. I really like the m2 but it's just a shame NAD couldn't provide a simple line out. NAD has documentation on sub integration but much will depend on the sub itself. I think it's best to contact individual manufacturers. I live in Dallas but I am really an Htown boy.
I narrowed things down to Def Tech's Supercube Reference and Martin Logan's Depth. I will get the reference. ML never responded to my question. However, Def Tech responded with the following answer:
"It would be quite acceptable to connect an LFE cable to our SuperCube subwoofers while connecting a set of high level inputs to the subwoofer. The subwoofers would combine or sum together any bass they receive from the speaker wires with any bass they receive from the LFE cable. The subwoofers would then play any – and all bass they receive."

thanks for all of your help.
Big D, tell me how you like it. I am going to go with 2 Supercube I's. That Supercube Reference is going to be a beast compared to the B3.