The Cambridge 840c was borrowed before and tried in my system and I thought it had more bass and a bit more detail and deeper soundstage than my sub 200 dollar Oppo.
The 840c had a 175 dollar power-cord (don't remember brand). The Rega has it's stock cord. I'd also like to mention that the Rega is a demo unit and broken in, but I'm auditioning with it's new stock cord only.
With the Oppo connected to the Rega we listened to the same tracks I had tried previously, especially the Groove Note sampler. We were able to switch between the two units on the fly.
The Cambridge was detailed and more up front than the Rega. Bass was about the same, but the Rega had a small edge in lower end detail. Since I'm running a sub, we turned it off to be certain and the Rega retained the lead in bass with the Merlins playing on their own. My friend and I did not agree on the midrange. He felt that they sounded almost the same, but I thought the 840c's more forward presentation was better for vocals. At the higher frequencies the Rega sounded sweeter and less anylytical than the 840c. Very high frequency sounds had the same detail from both players, but they were "softer" from the Rega. I really couldn't say which was more accurate, but the Rega was easier to listen to.
Soundstage on the Rega was better, but once again it only seemed obvious on classical recordings. Here the Rega conveyed the scope of the recording venue better than the 840c. That 3D feeling is something I thought my previous systems could do well, but the Rega has taken it to another level. I'd like to point out that either setup sounded terrific and you'd have to be crazy to suggest that one or the other could impede anyone's enjoyment of music. The synergy of the Rega with the Manley Stingray tubes must also be considered as in other pairings the 840c may sound far different.
We did not have time to pair the Rega with the 840c, but as I will most probably be buying a Rega from Signature Sound I'll have the chance to try that at a later date.
Thanks for reading.
Rob