are some phono stages more resistant to hum?

You also may have wired your cartridge incorrectly. If your wire joins the shield and the "negative" lead then you could get hum (I don't know the specifics of your wiring harness).

But make sure you've plugged in the right color wire to the right cartridge pin. One way to be sure is to use an ohm meter with the phono cable unplugged. Then check ohms between the blue wire and the shield for the RCA jack of the left channel. Ohms should be very low 0.3 or something like this. Then do the same for green and the right shield for the RCA jack. Now do the same for the right channel RCA jack tip and the red wire (0.3 ohm or less) and the white wire and the tip of the left RCA jack.

Now check a metal part of your tonearm (between the headshell and the bearing in case your bearing has a plastic cup) and see if it has a low ohm reading to your ground wire.

Noisy tube in the AR unit?

thank you, will try all these things. I did try different tubes, not the problem.

when I do not connect the ground wire from the tt, just leave it dangling unconnected to anything, the hum is greatly reduced. What does this imply? problem with the way the entire system is grounded? I live in an apartment, and have no control over the non-audiophile wiring setup.

There are probably a dozen reasons why one phono stage might be more likely to hum with a particular tonearm and cartridge where some other phono stage will not. First of all, lets get the terminology straight; when you say "hum" it implies a 60Hz or 120Hz tone (in countries where the mains frequency is 60Hz). Hum is almost always due to inadequate grounding. By that definition, tube phono stages are no more likely to hum than SS ones. However, true balanced phono stages of either type are much more immune to hum than are single-ended circuits, because even if the ground scheme is not perfect, hum in a balanced circuit is often cancelled by the mechanism of Common Mode Rejection (CMR). The better the CMR (i.e., the more the two halves of the balanced circuit are truly in balance), the more the phono stage is impervious to hum. One kind of noise that is akin to hum is the rare instance where the cartridge will interact with the tt motor, some types of which can induce hum in the cartridge. "Bad" tubes can sure be noisy, but the noise does not usually have the quality or pitch of hum.