Tube noise or "tube rush", is usually a very quiet but constant sshhh sound through the speakers. With some designs it can be accompanied by a low level hum as well. The amount of noise depends on the design of the circuit it is placed in and the quality of the tube. At normal/acceptable levels you can hear it when you put your ear within a foot or so of your speaker with no music playing. This is not significantly audible from the listening position and obviously doesn't compete with the music. Nonetheless, it contributes to a subjective sense of dynamics not leaping out from as black a background. Tube afficianados value the sound they impart above issues of low level noise. In your case, as I said, it may be a borderline issue.
Tubes specially selected for low noise or super low noise can be purchased expressly for use in phono stages. It is generally thought a waste to use them in line level situations where the input signal sufficiently overwhelms whatever low level noise the tube may be contributing.
As far as the gain being possibly insufficient for that cartridge, that depends on the cartridge output and the combined gain of the Cary, your line stage and amp, coupled with the sensitivity of your speakers as well as your habitual listening volume. Your cartridge's output is listed as 2.5mV but this is measured @ 3.54 cm/sec. This is perhaps more often measured @ 5cm/sec which would give you about 3.5mV. Most MM carts are rated between 3.5 and 5mV@5cm/sec with some up to 7. The other issue is, as I said above, the gain may be sufficient but with the volume turned up higher than usual on your preamp, which may begin to reveal the tube rush a bit. If you typically, or at times, listen very loudly and you have speakers with below average sensitivity (below 89 dB) then the tube rush may get to be more than you are willing to put up with.
Aside from explaing the whole picture, this is also to say that I can't answer your question without more info. If you want to play it safe you can avoid tubes. That hasn't been my choice and, in fact, I am battling a noise situation of exactly this type at the moment. Mine is more extreme than yours in that I am using a cart with a .4mV@3.54cm/sec output, which translates to about .56mV@5cm/sec output, with a 42dB gain tube phono stage into a low wattage tube amp driving speakers of 89dB sensitivity. For some records I am barely at the desired volume with my volume knob all the way up. At this setting my amp is starting to add a bit of noise as well. Dynamics begin to be affected also. Ideally, I would be using a cartridge with twice the output or a phono stage with another 6-12dB of gain or speakers of 94dB sensitivity or more, although having more sensitive speakers wouldn't be as effective at reducing noise. A doubling of voltage is required for every 6dB of gain so something like 1mV@3.54cm/sec or 1.4mV@5cm/sec to twice that output or a phono stage with 48 to 54dB of gain would suit me better.
Incidentally, all circuit components generate noise, even resistors and transistors. It is always necessary to choose low noise components when designing phono stages and they are usually more expensive. For instance, Vishay bulk metal foil resistors are $4 to $25 as opposed to the average high quality metal film resistors at about 20 cents.
Given your system, I would be looking in the $1k plus range for a phono stage. There are many good contenders at this price: EAR, Musical Surroundings, Heed, Sutherland, Acous Tech, ASR, AES, PS Audio, Graham Slee, Sim Audio, Wright Sound and others. Wright Sound and AES (Cary) are the only tube designs in this price range I can think of.
I hope this helps clarify your situation. Good luck and enjoy!
Tubes specially selected for low noise or super low noise can be purchased expressly for use in phono stages. It is generally thought a waste to use them in line level situations where the input signal sufficiently overwhelms whatever low level noise the tube may be contributing.
As far as the gain being possibly insufficient for that cartridge, that depends on the cartridge output and the combined gain of the Cary, your line stage and amp, coupled with the sensitivity of your speakers as well as your habitual listening volume. Your cartridge's output is listed as 2.5mV but this is measured @ 3.54 cm/sec. This is perhaps more often measured @ 5cm/sec which would give you about 3.5mV. Most MM carts are rated between 3.5 and 5mV@5cm/sec with some up to 7. The other issue is, as I said above, the gain may be sufficient but with the volume turned up higher than usual on your preamp, which may begin to reveal the tube rush a bit. If you typically, or at times, listen very loudly and you have speakers with below average sensitivity (below 89 dB) then the tube rush may get to be more than you are willing to put up with.
Aside from explaing the whole picture, this is also to say that I can't answer your question without more info. If you want to play it safe you can avoid tubes. That hasn't been my choice and, in fact, I am battling a noise situation of exactly this type at the moment. Mine is more extreme than yours in that I am using a cart with a .4mV@3.54cm/sec output, which translates to about .56mV@5cm/sec output, with a 42dB gain tube phono stage into a low wattage tube amp driving speakers of 89dB sensitivity. For some records I am barely at the desired volume with my volume knob all the way up. At this setting my amp is starting to add a bit of noise as well. Dynamics begin to be affected also. Ideally, I would be using a cartridge with twice the output or a phono stage with another 6-12dB of gain or speakers of 94dB sensitivity or more, although having more sensitive speakers wouldn't be as effective at reducing noise. A doubling of voltage is required for every 6dB of gain so something like 1mV@3.54cm/sec or 1.4mV@5cm/sec to twice that output or a phono stage with 48 to 54dB of gain would suit me better.
Incidentally, all circuit components generate noise, even resistors and transistors. It is always necessary to choose low noise components when designing phono stages and they are usually more expensive. For instance, Vishay bulk metal foil resistors are $4 to $25 as opposed to the average high quality metal film resistors at about 20 cents.
Given your system, I would be looking in the $1k plus range for a phono stage. There are many good contenders at this price: EAR, Musical Surroundings, Heed, Sutherland, Acous Tech, ASR, AES, PS Audio, Graham Slee, Sim Audio, Wright Sound and others. Wright Sound and AES (Cary) are the only tube designs in this price range I can think of.
I hope this helps clarify your situation. Good luck and enjoy!