Change from Spectral

Unsound, I guess if both are designed to use together, I would think that would be best.

I don't think it was cap coupled, and I was not the only person having this happened to them. Perhaps later versions had caps added.

TBG, I thought the SP6 was cap coupled? I'm not familiar with the Electro-Research amp. If the amp was DC coupled I'm not surprised you had a problem when DC leaked from the ARC cap coupled pre. This example only supports my idea that DC coupled amps are best used with DC coupled pre's.

Unsound, I am sure that it is because of dc getting to the amp and frying the speakers. This did happen to me a long time ago when my ARC SP6 turned off at low voltage and turned on again putting out dc into my Electro-Research amps and fried my Linn IsoBariks.

That "using both a pre and amps dc-coupled is NOT at all a good match." is news to me. Spectral, at least in the past, only made DC coupled pre's and amps, as well as Atma-sphere, Krell, etc.. I suspect (for some time, it was srongly recommended) that Specratal would want their customers to buy and use their gear together. Some have argued that balanced, low impedance, direct-coupled designs have some advantages. Many DC couple designs use a servo-mechanism that would might offer greater protection from DC leakage than caps might provide. I'm sure SF knows what's best for their gear, but I sure would like to know the reasons behind SF's recommendation.

You are seeking protection from dc getting to your amp and frying your speakers. I am sure that a good technician could put a cap in either your line stage or amp to block it. It might affect your sound, however. Designers would prefer there being no unnecessary caps in the circuit. I would call Spectral and express your concerns.

I wrote to the Sonic Frontiers guys, and they are telling me that using both a pre and amps dc-coupled is NOT at all a good match.
I wrote to some hifi italian forums too, and got the same theorical reply.
I am happy with the sound, but maybe the pre especially is not working properly due to the offset dc current.
Now I have a test to do....
I am happy with the sound, the Line3 and Spectral!!!

Why do you need to change?