If you are now questioning your overall audio performance with these killer speakers, my guess is that the problem would likely be the compromises and warts with your source and/or the room acoustics ..... And not your REGA amp.
Not all Rega amps are built to sound the same. I owned the Rega Elicit mk2 and the Harbeth SHL5 sounded lacklustre when matched with it.
I would imagine the Osiris to be the best sounding Rega amp, followed closely by the Aethos. The lower range Rega integrateds are suboptimal if your system is above average, particularly if you own some Harbeth speakers.