Can anyone with an Opus 21 who uses a Ridge Street Audio amblical advise me of the performance of this upgrade please?
I've had a chance to hear the opus with and without the Ridge Street and frankly, there's no comparison...
Ultrafitimes...I assume that you are indicating that the Opus 21 with the Ridge Street cord is the hands down winner and worth the expense?
Owning an Opus 21 and the Exousias Umbilical from RSA I thought I'd do a comparison. I've had the Exousias in place for many months now,honestly I forget but maybe a year and a half even.

Now to divert for a moment. One of my fine upstanding Credit Card Banks recently doubled the Interest rate on a rather large balance due only to their own need to raise revenue and not for any breech of their terms on my part. The thought I might sell my Exousias came to mind that I might pay down that balance so before I composed an email to make such an offer I put the stock cable back in.

You may or may not be aware The designer of the Opus 21 has publicly commented about this cable. What I hear however ,in light of what I've stated above, is rather apparent in that timbre sounds livelier with the Exousias in place. An over all more mellifluous radiance is to me perceptible which is I thought, rather obvious when replacing the stock cable.
With that the same music (Rachmaninov's Sonata in G minor for Cello and Piano Op. 19 on a Naxos CD) seemed to sound less lively, somewhat heavier in that it seemed to fall off much sooner whereas with the RSA Umbilical the notes come more fluidly with greater vibrancy and more reality to them. I was for all intents and purposes ready to let it go if an offer had been accepted . Now I am not as eager to make it available.
I am aware of phenomena like Placebo Effect and that other factors always influence perception but in spite of it all I do consider that I am hearing a desirable improvement in the music I hear thru this player with the RSA Exousias in place. Weather the price is justified is a matter for the Manufacturer and the Customer. Geoff Kalt's comments were surprising and I imagine some would prefer I hadn't brought them up but I have to account somehow for what I hear.

I looked at what I understood of the Opus 21 player. Its power supply separate from the DAC with that current supplied over the Umbilical . That current is of what the Signal is composed is it not? In a sense it is the music. It is created with the electric current and in that form delivered via the Amplifier to the Speakers and then your Ear/Brain. Without access to Lab Testing it would seem that if the current from which the Signal is constructed at the DAC is delivered with more optimal conditions that Signal would be better when arriving amplified at the Drivers. Something has to account for what I perceive. I believe I could in a blind test discern between the two cables but I am hesitant to urge anyone to act as I have. The Company does offer a money back refund for I think 45 days so you have little to lose and if you're near New Hampshire I'd be willing to have you come listen for yourself.

Either way I'd be interested to hear what you do and what you find. Good Luck.
Adri, thank you for your information. I did not know that the designer of Opus 21 commented on the RSA cable. Please tell.. what do they say of the RSA cable? If you do decide to let yours go, please email me.