Long cable run from my phono preamp to linestage.

Al, I've got a similar situation going. I'm running a 15 to 20 foot SE run from my phono pre to my linestage. No ground loop or hum problems that I can detect.

The output specs of my ARC Phono Pre 8 are 200 ohms unbalanced; recommended load is 50K-100K ohms and 100pF.

And the input specs of my REF 5 SE are 120K ohms Balanced; 60K ohms SE.

Tom Tutay made custom SE I/Cs for me. I recall he said the I/C capacitance is 19 pF per foot. I guess it would be better if I could shorten the run to 5 or 6 feet. Oh well.

Assuming my I/C capacitance is about 400 pF, what impact would that have on the signal??

George, just an fyi, both of my ARC units are tube. But, aside from the electrical characteristics of the SE I/C, ARC gear is designed to be extremely synergistic with other ARC gear.

Btw, just inserted a DEQX Premate in between my ARC Ref 5 SE linestage and Ref 150 amp. Was a bit concerned about impedance compatibility, but all is well. Little nervous about inserting an artifact in the line signal too. But I think the DEQX benefits greatly outweigh whatever downsides there may be.

George ... please remind me how you know about DEQX. There's been so many threads and posts, I forget who said what.

Take a look at some of my posts. I think the DEQX Premate has done a great job squeezing everything out of my Paradigm S8s (v3) that they can offer. The DEQXpert had a devil of a time aligning my S8s. He had to use my self powered subwoofer to do a lot of low end bass lifting because the tweeter/midrange drivers are wired in reverse polarity as compared to the onboard woofers. Time alignment is not perfect, but much better. The cross over between the sub and the onboard woofers is about 120 Hz. It's all about compromises.

Also, my room wreaked havoc on the FR. The DEQX mitigated a lot of room problems.

Overall, imaging, coherence and sonic hue is much improved.

George -- I respect that. IME, using the DEQX came down to weighing sonic benefits against sonic costs. I gotta believe that inserting the DEQX into the signal path has cost something in the sonic sense. But, there are clear sonic benefits that outweigh those costs.

Time coherence mumbo jumbo aside, the room EQ correction alone is a major positive. I thought my finished basement/ sound room provided a great sonic environment for my rig. Nice plush sofa, a guest bed, carpets, plants and so forth.

WRONG!!

The DEQXpert carefully measured each speaker's FR at my listening position. The separate and combined FR plots were a mess, especially in the all-important bass and midrange spectrum. That alone caused major image smearing.

Of course, time aligning the drivers helped a lot too. Much more coherent imaging and less congested presentation.

I think many of our fellow hobbyists would be really surprised at just how sonically toxic their sound rooms may be. After all, the better speakers brands are probably voiced in an anechoic chamber. But that's not how the real world is.

The DEQX did some major signal twisting and bending to smooth out my speakers. They are NOT ruler flat ... nor perfectly time coherent. But they are "tamed" for lack of a better way to describe them.

So what's worse? Twisting and bending the signal being fed into my speakers, or letting one's sound room to bend and twist what comes out of the front end of the speakers by the time the sound reaches the listening position. Distortion is distortion.

Of course, the alternative is that one could turn their sound room into a sonically dead anechoic chamber and buy time coherent speakers that look like one eyed insects or Dr. Who Daleks.

Just my humble opinion. LOL