I have actually heard a Naim amp that a friend had that we attempted to pair with tube linestages. The result, with several models was not that satisfactory -- sluggish, murky sound. Of course it might have worked well with a different linestage. As with any kind of matching, one has to actually try the particular combination to know if it will work well. From my experience, the least predictable match is a tube linestage/preamplifier feeding solid state. I am not saying it would be bad, but, I have heard enough combinations that were not good so I would say the results are highly unpredictable. The other way around is much more predictable -- the particular characteristics of the solid state linestage seem to carry over more predictably when coupled with a tube amp (this may too be a disappointment if one had hoped to somehow radically change the sound).
The other thing to consider, when going to tube feeding solid state, is whether you intend to keep the solid state amp on all of the time (usually helps the sound and is, I believe, the recommended practice for Naim amps). If that is the case, you will be switching on the tube linestage while the main amp is active. A tube amp being turned on, and some when being turned off, can emit pretty nasty noise. Some tube gear cures this problem with a mute circuit that either automatically mutes at turn on, or requires manual muting until the unit is warmed up. This is not an issue with all tube systems where it is common practice to turn the amp on last and off first.
I don't know if a tube linestage is more likely to produce dangerous, speaker threatening impulses. I have actually experienced more problems in that area with solid state gear myself. the primary maintenance issue with a tube linestage is aging tubes that will cause deterioration in sound quality (typically making the sound dull and lifeless) or result in increasing noise. I would have an extra set of tubes ready for replacement and "testing" (every year or so, try putting in the replacement tubes to see if the sound of the original set has deteriorated enough to warrant replacement). Apart from tube replacement, tube gear tends to last quite a long time and is repairable (solid state gear is more likely to become unrepairable because of unobtainable transistors and ICs).
The other thing to consider, when going to tube feeding solid state, is whether you intend to keep the solid state amp on all of the time (usually helps the sound and is, I believe, the recommended practice for Naim amps). If that is the case, you will be switching on the tube linestage while the main amp is active. A tube amp being turned on, and some when being turned off, can emit pretty nasty noise. Some tube gear cures this problem with a mute circuit that either automatically mutes at turn on, or requires manual muting until the unit is warmed up. This is not an issue with all tube systems where it is common practice to turn the amp on last and off first.
I don't know if a tube linestage is more likely to produce dangerous, speaker threatening impulses. I have actually experienced more problems in that area with solid state gear myself. the primary maintenance issue with a tube linestage is aging tubes that will cause deterioration in sound quality (typically making the sound dull and lifeless) or result in increasing noise. I would have an extra set of tubes ready for replacement and "testing" (every year or so, try putting in the replacement tubes to see if the sound of the original set has deteriorated enough to warrant replacement). Apart from tube replacement, tube gear tends to last quite a long time and is repairable (solid state gear is more likely to become unrepairable because of unobtainable transistors and ICs).