Preamp for audio research ref110

For short term you could run an RCA to balanced cable from the SP9 to Ref.110.

I suspect that like most or all of the the more recent ARC Reference series amps the Ref 110 won’t work properly when provided with unbalanced signals via adapters or adapter cables. In the more recent designs, at least, apparently only half of the balanced signal path within the amp would see a signal in that situation, resulting in a drastic reduction in power capability among other consequences.

If ARC confirms that is the case with the Ref 110, what I would suggest is that you purchase a Jensen Transformer, probably their model PI-2RX (similar to the PI-2XX shown at the link except with RCA input connectors). Give Jensen a call to confirm that would be the best model to use in your specific application. It would convert the unbalanced signal for each channel to a true balanced signal pair. It would also eliminate any possibility of ground loop issues between the preamp and power amp, and would provide noise rejection comparable to the performance of a fully balanced interface. It would require that you use a very short length of XLR cable on its outputs (no more than about 2 feet or so), but the length of the RCA cables connecting to its inputs is not critical.

Good luck. Regards,
-- Al

I think I will get an RCA to xlr converter until I get the real thing. Seems like these are available from pro-audio shops.

Given the previous comments by Docknow (thanks!) and myself, I assume you are referring to an active converter, i.e., one that contains powered circuitry. If so, a point to keep in mind is that like many and probably most ARC line stages and preamps the input impedance of the device to which the SP9 MkII is connected should be relatively high. From its description at www.arcdb.ws:

Recommended load 60K ohms and 100pF. (20K ohms minimum)

A lot of pro audio equipment will not meet that requirement, not even the 20K minimum.

A transformer-based converter, by the way, such as the Jensen I referred to earlier, will easily meet that requirement when used in conjunction with your particular power amp, and when used with many and probably most other amps as well.

Regards,
-- Al