Threshold Fet 10E bi-amping question

I am currently bi-amped with 2 Threshold S-300E Series II amps, and a Threshold Fet 10E pre-amp. Since the Fet 10E only allows 1 balanced out, and 1 RCA out, to bi-amp, I have to use both. I was in touch with Jon Solderberg of Threshold, who updated & refreshed all of my equipment, new caps etc... And he said he thought the Fet 10E HL should be able to drive both amps. I've since lost touch with him, but had a tweeter go out on my B&W matrix 802 Series 3 speakers. And now I find no way of contacting Jon. I had one amp running the mids and tweeters, and one running the bass drivers. Due to all the hurricanes we've had in Florida, everything is unhooked and stored safely, but I am dieing to put the system back together. Am I better off running the tweeter/mid amp on the balanced input amp (Tice XLR crio treated inter connects) or the RCA amp (Audio Quest Emerald)(both identically matched amps)? The tweeters were a bit bright to me before, and I don't think the Threshold gear is. Unfortunately, I can't remember how I had it set up last. I would like some input before I buy the new tweet and hook it up again. Also could you please give me the correct replacement tweeter model number?? That would also be a huge help. Thanks for any advice you can give me. Tom
I also have a Threshold Fet 10e and S350e power amp. I briefly had my system bi amped with a loaner amp " Threshold 400a" I didn't have balanced cable at the time and just used a RCA spliter connector and the Fet 10e seemed to drive both amps fine. I am currently just using the single amp "S350e" with a pure silver balanced XLR interconnect "Signal Cable Silver Resoslution". I would most definately recommend the balanced cable on the amp driving the top end, midrange and tweeter. I found the sound to be much more open, smoother and transparent with better detail using the balanced connection. I have tried to contact Jon Soderberg also with NO success. What's up with that? I was considering getting a sub woofer and driving it off my umbalanced pre output but when I called Threshold about it a guy told me that the Fet 10e was only meant to use one output, either the balanced OR the unbalanced but NOT both. Personaly I think the Fet 10e IS up to the task as I did drive two amps with it before just as you have and feel that it should also be able to handle a subwoofer amp also. One thing I find strange about using the balanced XLR connection is that they say there should be a 6db increase in gain due to the balanced connection BUT for some reason I seem to be noticing a slight LOSS in gain with the Threshold equipment. The sound is great but it seems like I have to turn it up a couple of notches louder than before. I was trying to contact Jon about this but no luck. Hope this helps, if you have anymore questions or just want to chat Threshold, feel free to email me.
Others have reported the loss of gain using the balanced out of the Fet ten/e into an e series amp. Must be normal and maybe due to the equal impedance characteristics.

Jon's link is active if you need it:
Hi Arnold, thanks for the input. I had Jon's street address on the box he used to return the last equipment he updated for me, but in all the Florida hurricane scares, I seem to have lost it. My garage floods and I'm thinking that box must have gotten wet. If ANYBODY out there has his street address, please POST IT! I have spoken to him a number of times at his home, and I'm pretty sure he would be listed. As far as your bi-amping situation, I never noticed any gain difference on the RCA vs. balanced, when bi-amping. Jon updated both amps to E spec and series II, which I would think would be extremely similar to the S350E, and some where I remember Jon saying my power out put would increase with these upgrades. BUT, Jon would know for sure. I wouldn't think you would experience a gain loss if you are no longer splitting the same signal?? Possibly though, as the balanced circut in the Fet 10E is independant of the RCA. So we really need to find Jon to get accurate answers. Hopefully some one on here can put us back in touch with him.... Tom
Ya can lead a horse to water...
Thanks Rockvirgo, although that link is dead, the address and phone number is exactly what I needed. Tom
I have the FET 10/E with the same issue when using the balanced output. I have to turn it up couple of notches louder than using is nothing wrong
I believe that unlike the original factory made Threshold e series amplifiers, the Threshold e series pre's are not truly differential balanced designs.