Lyra Lydian Beta, Rega hum?

Yes Franks, The hum is too loud to listen to and it starts as soon as take phono preamp off mute. Guess I need to get it checked out.

Before you give up hope - try a few different carts - if you can. If they all hum about the same then you've a problem with the p25/600.
I personally couldn't tolerate the P25/600 with its earthing/motor shielding quirks and changed to another brand of t't; and haven't been happier.

Still think it's the cartridge, but one other possibility has occured to me. Is the cable from the phono stage to your line stage shielded? If not, this can be a considerable source of hum. Let us know how this turns out.

David, i've never told that the hum is from the table. There shouldn't be any grounding problems with RB300 either except when there are some manufacturing deffects.

The first party to call should be Immedia to report a problem with the cartridge.

BTW do you connect this setup the first time or you used different cartridges prior?

This rig is all new. Bought the cartridge from overseas seller. Last night I shut my amp off and listened with headphones through my Sonic Frontiers line 2SE headphone jack. There is a hum in stereo, but when I switch to mono the hum is at such a low level it is not a problem. Why would it hum in stereo and not in mono? When I use mono through amp and speakers hum is lower than stereo, but not really tolerable.