Integrating a sub with a Rossini

This question may apply to Vivaldi and Bartok as well.
I recently purchased a Rel S/510 sub to add some bottom to my Maggie 20.7s. Rel claims the best way to integrate a Rel sub is via the high-level output option going from the amp’s speaker terminals to the sub using the Neutrix cable Rel provides.
Has anyone compared this high-level output option to a low level output using the RCA (unbalanced) outputs of the Rossini? I seem to be getting deeper bass and better integration using the low-level RCA outputs of the Rossini.

These next questions may be for Andrew.
Is there any degradation of the SQ using the XLR (balanced) outs to drive my amp and the RCA (unbalanced) outs concurrently to drive a subwoofer?

Would there be any advantage to avoid using RCA (unbalanced) cables altogether and go from the Rossini to the Rel sub via XLR inputs and from the Rel XLR outputs to my amp?

Brian …

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Not exactly but in a broadly comparable way some years ago.

REL have always recommended the high level output option from the main amplifier .

I last used a REL sub with a dCS front end back in the days of the first generation i.e. an Elgar Plus based stack. This was with Quad ESL 63s and ( if my memory is correct) Naim amplification. My experience was that, in that setup, REL were correct in their judgement.

However that is only my opinion so feel free to experiment and make your own mind up.

I don’t want to pre-empt Andrew but as I understand these things the single ended and balanced outputs of all dCS DACs are properly buffered so there should be no problem in using both to drive the REL amp and the main amplifier simultaneously. I would say, however , that the single ended and balanced analogue output circuits are often (usually?) of a different nature in dCS DACs ( one being opamp based the other fully discrete) . I do not know if this is the case with Rossini though whether it would be subjectively significant for the envisaged purpose I cannot say though I probably doubt it.

I would imagine ( and it can only be that having no hands on opportunity ) that driving your main amp input via the XLR output option of the sub would be the worst sonic option even if electrically compatible.

Thanks Pete. It turns out using XLR cables from the Rossini to the REL is not an option The XLR inputs on the REL are for .1 LFE (Cinema). I’m quite happy with the sound and coherence I’m getting using XLR from the Rossini to drive my amp and single ended RCA from the Rossini to drive the REL sub. As you mentioned in your reply, let’s see if Andrew has a reason why this may not be the optimal setup.

I’m also guessing REL came up with this connection method of using the high-level output of the amp to drive the RELs to aid sales. Any potential customer can tap into their amp terminals to feed a REL, with the possible exception of active speaker owners. But perhaps not everyone has an extra pair of unused XLR or RCA terminals on their pre-amp.

“… don’t feel like you’re compromising your system when connecting using this method.” (in relation to using the RCA inputs on the REL).

Enjoy :slightly_smiling_face:

Bad luck on the XLR connection. Thinking back to the early days of REL when it was owned by its founder the late Richard E. Lord the high level connection was devised to preserve the sonic characteristics throughout of the main system to which it was connected. The connection in those days was made by a banana terminated cable with stacking bananas at the amp end ( spade connection may have been available but I don’t remember - I am pushing a 30 year old memory). The Neutrik speakon connector came much later.

At that time most integrated amps or preamps came with a tape loop and the REL subwoofer could be connected using tape out as an alternative to the speaker connection.

Thanks Anupc & Pete. Another disadvantage of the high-level option is I have a rather loud hum coming from the REL even after using an RCA cable connected from the Rossini RCA out to the REL LFE RCA input as REL suggests I even had to use a cheater plug as the hum was so prominent. No hum using the low-level option.

I’ll let my ears be the judge whether to use the high-level or low-level inputs of the REL.

Hi Brian,

No, there is no degradation of the sound quality caused from using both the XLR and RCA outputs simultaneously. Inside the Rossini, the output stages are separate so do not have an impact on each other.

Just make sure you are using the correct (balanced/unbalanced) connection on the other end of the Rossini outputs, and you’re good to go.

Thanks James.