10 meters of interconect cable is too long.

A 30 foot speaker cable is much better than a 30 foot interconnect...........

It depends on many things. And over the years there have been a number of threads here in which the question of long speaker cables/short interconnects vs. short speaker cables/long interconnects has been discussed, with my perception being that a clear majority favors short speaker cables/long interconnects in most circumstances. In fact one of the advantages of monoblock amplifiers is often considered to be that they make it possible to have very short speaker cables.

Some of those dependencies: Preamp output impedance (the higher this is the more important it becomes to keep interconnects short, everything else being equal); speaker impedance (the lower this is the more important it becomes to keep speaker cables short, everything else being equal); balanced vs. unbalanced interconnects (balanced interconnects tend to handle long runs better); preamp compliance with balanced standard AES48 (which minimizes the importance of interconnect length); the internal grounding configurations of the preamp and amp (which affects susceptibility to ground loop issues, which is also affected by the resistance of the shield or other return conductor in interconnect cables, and resistance is proportional to length for a given cable type); and of course the characteristics of the specific make and model of the cables.

Regards,
-- Al
 

... next project will upgrade preamp with xlr connections.

FYI, simply adding XLR connectors to the preamp will not help, because you would still be sending single-ended signals into the cables. Unless, that is, major modifications were made to the preamp to allow it to generate true balanced signal pairs for each channel. That would likely involve addition of a tube, physically large output coupling capacitors, and other circuit elements, assuming there is room to fit all of those things.

Simply adding XLR connectors, while providing them with unbalanced signals, might result in minor sonic differences compared to running long RCA cables due to differences in the cables that are used. But those differences could just as easily be for the worse as for the better, compared to running long RCA cables.

The transformer approach I suggested is far more likely to be a good solution.

Good luck. Regards,
-- Al

Yes, unfortunately you are likely to experience some degradation of sonics at that length, especially given that the interconnections to the amp are single-ended. And a simple RCA-to-XLR adapter at the outputs of the preamp will not help.

However you may want to consider connecting the outputs of the preamp to a Jensen PO-2RX transformer, via short unbalanced interconnects, and connecting the outputs of the transformer to the amps via balanced cables. That would result in the long cables being driven with a true balanced pair of signals. Although in doing so the relatively high output impedance of the preamp (measured by Stereophile as 370 ohms in the midrange and treble, but rising to a very high 6.8K at 20 Hz) could conceivably still be an issue, as the 1:1 turns ratio of the transformer will not change the impedance with which the long cables are driven. Trying it is probably the only way to be sure.

Regards,
-- Al