Since Thomas OK set up your table ( which with the new upgrades should be stellar), I would not expect any issues with the table. OTOH, hum is usually caused by an improper grounding scheme. You should be sure that the Bryston and the tonearm phono cables are grounded through your preamp...( making sure that the connections are clean and good on the grounding wire!). If the problem persists, i would check and see if the phono stage is grounded and if the preamp is likewise.
If the hum is still an issue ( and it sounds like it might not be hum at this point), then i would be tempted to have the Bryston looked at by a Bryston rep. One other thing, if I remember correctly from the time i was listening to the Bryston, it has dip switches inside it to adjust the gain, you should make sure these are set for the value of your new cartridge!