Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Balanced from 861v8 to unbalanced 258 power amp

I have purchased a 258 power amplifier that I want to use for rear and side channels, but I have two OA18 cards in my 861v8. Can I use an XLR to RCA Phono adapter cable or do I have to buy an OA08 card to replace one of my OA18s?

Yes, you can use a adapter or create a XLR to RCA cable.
My amps for the rear, centre and the sub are also connected using such cables as they only have RCA connections.

For XLR to RCA cables, you have two types; Shorted and Open. I'm going to assume Open (on the -Neg differential wire) would be correct.

Outside of that, your other options are active and Passive XLR to RAC converters, these retain the noise suppression of XLR (if required).

Passive options are transformer based, while active are typically op-amps. would avoid a cheaper transformer based solution (they will induce noise at low frequency), personally used Jenson ISO max series with no issues.

XLR adapters seem to work fine and cost just a few quid each.
Used them extensively in my old system to various devices with XLR only inputs from an 861 v4 with unbalanced out.

There is an earth wire in them that might not be the best quality, most are probably made in China, but without changing out the earth for a Van Damme or something similar, it's hard to know if there would be any difference.

Also have a balanced card for the 861 and used that once, but couldn't tell any difference between the two methods so took the balanced card out for simplicity as needed to split the fronts which was easier with RCA.
Save some money and buy the adapters, or buy a made up XLR to RCA cable.
Always found Lynx cables sounded good for mid range / neutral and cheap, other cables tested were often brighter sounding, better for tweeters only.

Thanks for all the advice, I think I'll try to make my own cable adapters with quality components on the connectors. I was thinking of using Neutriks XLR NC3FXX-BAG connectors and Neutriks NF2C-B/2 phono RCA with Supra cable, but not connecting ground on pin 3.
I don't think there's a need for a converter as the cable length is only one meter.

XLR Pin Connects to RCA
Pin 2 (Hot) RCA Centre Pin (Signal) The audio signal itself.
Pin 1 (Ground) RCA Outer Ring/Shield (Ground) The ground reference.
Pin 3 (Cold) UNCONNECTED (Floating)

Have tried to find characteristic data on 861 and 258, I have found this data, is it correct?

The output impedance is 47 Ω on the Meridian 861 XLR output (balanced OA18)
The input impedance is 16 kΩ on the Meridian 258 power amplifier (Unbalanced)

861 Preamp XLR Output (Balanced OA18) 4.5 V RMS
The voltage will drop by approx. 6 dB, i.e. from approx. 4.5 V to approx. 2.25 V RMS in the transition to unbalanced.

258 Power Amplifier RCA Input (Unbalanced) 1.0 V RMS Nominal level to drive the amplifier to full power.

The Rane Tech 110 is my go to for interconnecting, there is a pdf download link at the bottom; number 4 is the one you need.

All the best,

Steve