... Should I be concerned?

Also, here is the link to the Brent Jessee website's  12ax7 page , you might find his take on the different 12ax7 variants and brands helpful

http://www.audiotubes.com/12ax7.htm

@insearchofprat.....I am going to answer this from a different angle, and it is my experience, I say this. With the input level controls on the Parasound, set low, initially..............bypass ( do not use ) the tube line stage, and go direct from the Marantz SA 8001, into the Parasound. The SA 8001 puts out greater than 2 volts, and has one of the cleanest, least distorted output stages, and has a hefty, beefy, analog output stage / power supply, in an all in one cd player. Enough clean, hefty voltage, to drive your amplifier to full power. This will be " passive ", without the additional gain, to drive the power amp. Some posters here ( possibly all ), will disagree with me, on the passive mode, which is fine. I am suggesting doing this, for a week or so ( although it will be a pain to operate the rear controls on the amp ), because I have found, all line stages, especially tube products, to add colorations ( some say, additional warmth, smoothing over, just as a few examples ), and, robs you, of the finite details and information, embedded in your cds. This a a big controversy, between using a gain stage, and going " direct ", or " passive ", and I guess, you figured out, what camp I belong to. Lots of reading, here and elsewhere, on the subject. If you only listen to this one source, and you like what you hear, going direct, you can contact georgehifi, here, and get from him, possibly, the best " passive preamp ", in existence. Anyway, enjoy, stay safe, and be well. Always, MrD.

So many suggestions. Use your ears. We can't tell you what sounds best.
We're not there.

Lowering gain of power amp is a good thing.  Overall gain from the source to speakers will be the same, but spread of the gain will change.  More gain will be allocated to pre (quieter environment) than to power amp (noisier environment), not to mention reducing noise pickup by ICs (higher signal level).
 I don't know construction of Parasound, but even if gain is fixed and you just lower the signal (volume pot), the level of the signal entering the box will be higher (better for S/N).  Yes, engaging Parasound pots puts them in the signal path, but reducing authority of preamp's volume pot (max power=wider angle) is good.  I would do what rodman99999 recommended, unless you can hear audible difference.

The controls on the back of the amp allow you to adjust the input gain on the amp so that the volume control on the preamp can operate within its optimum range.  There is no rule that says that those amp controls should be full on.  You can also use them to correct for a preamp with a balance issue with a dodgy volume potentionmeter.