Audio Research Corp Ref 5 SE

@ Phil -- could be. Search the Forum for my posts regarding a custom impedance buffer that was made for me to resolve this issue. The formula to compute combined impedance is: The product of Main 1 feed imp. x Main 2 feed imp, divided by the sum Main 1 feed imp + Main 2 feed imp. In my case, Main 1 feeds my VS-115 which has an input impedance of 300K ohms and Main 2 feed the customer impedance buffer which has an input impedance of 330K ohms. If you do the math, the combined impedance is 157K ohms. Run your calcs and report back.

Bif,
I'm glad I came across this and thanks for your input on the postings regarding the impedance buffer from Tom Tutay.

Here is what I got:

Main 1 (ARC Ref 250) 200,000 ohms X Main 2 (REL Gibraltar Sub) 10,000 ohms/(Ref 250) 200,00 ohms + (REL G1) 10,000 ohms = 9,524 ohms.

This is below the recommended. I would run both mains out balanced (with balanced to single ended Cardas adaptors at the main out from the preamp) but it still is below the recommended 20K ohms for the Ref 5SE.

I really wanted to go all ARC for synergy, but I'm not sure anymore.

Phil, stay all ARC. The synergy is worth it. Call Tom ASAP. Not only did his buffer increase the impedance shown of the sub woofer, his device even summed the left and right channels without shorting out the Ref 5's Mains. So, my single sub woofer is mono below 50 ot 60 Hz, and shows my Ref 5 a 330K ohm load. Tom charged me only $500 for the device, which is built like a tank. It's an active device that plugs into the wall. If Tom was to build a device for you that had an input impedance that matched the Ref 250s (200K ohms), your combined impedance would be 100K ohms, which is plenty.

When I replace my Synergy IIi with an ARC Ref 5SE, I will call Tom and let him know my situation. Again, glad I cam across this post.

Memorial Day Update on Ref 5SE: Have over 650 hours logged on the Ref 5, although much is idle time hours. I think the Ref 5 is probably broken in by now. It really sings. Very sweet pre-amp. Btw, a major change from an unexpected source. Just replaced the 6H30 driver tubes on my ARC VS-115 amp. Wow! Together, what a combo. Just love mny ARC stuff!