What is a better route, tube or SS preamp?

If you go the tube pre-amp route, newer ARC pre-amps are fine choices for all kinds of music, including rock and metal. I would be cautious with some tube pre-amps though especially for this kind of music. I use an sp16 with Class D amplifiers. It is hard to tell what amplification technology is used. It just sounds great! I like that!

Be aware that if you go tube pre-amp, output impedance is higher and for rock/pop/electronic music in particular to sound best, clean and dynamic, you should make sure input impedance of you amp is 30K ohms or greater. Many amps designed to work well with tube pre-amps are 60K ohms input impedance or higher. My Bel Cantos are 100K ohms input impedance. The higher the better though benefits of going too high may be marginal or not significant.

If not sure about impedance matching between a tube pre and SS amp, stick with a good SS pre-amp. I would be looking at Bel Canto pre-amps if it were me.

I also replaced an old Carver pre-amp with the ARC sp 16. Huge difference! Definitely worth a try!

In this hobby hopefully you'll eventually be able to try (own or at least audition at home) many different designs which will eventually refine your personal taste.

At my age the idea and practicality of lightweight and powerful solid state has been a hopeful search from the first 60's A/B to todays class D switchers. Underneath this silly quest was the reality of the second order harmonic presentation of tube amplifiers that I grew up listening to in radios and televisions from the fifties.

I came full circle last year and purchased a pair of affordable Bob Carver VTA 180s. Cool running, easy maintenance, and more than enough top to bottom power for todays speakers. Having rolled my third set of input tubes their presentation evolves, something that can't be done with solid state.

Don't get me wrong I'm not plugging tubes I'm just enjoying them, again. I still have a pair of Hypex nCore 400 switching amps in my studio. Nothing like a massively powerful solid state amp. Keep in mind what those people are using to make your favorite hard and heavy music.

I think you should try both designs as the old line between solid-state and tubes has been blurred. Most good designs these days are relatively neutral in tonal balance but you can still find the old "tube sound" or "solid-state" sound if you want it. IMO, it is good to get tubes somewhere in your system, and if so, tubes are much better suited to voltage gain (preamp or input stage of power amp) than they are at current gain (output stage of power amps). I have had Conrad-Johnson, CAT, and Essence tube amps and they do all of the things SS amps do. However, since you have a tubed CD player output (don't know if they are voltage gain or cathode followers), a good SS design may be just fine. I think you are correct in listening to both and see what you like best.

"I know I need to demo some of both, but...”

No buts; that’s the answer.

Again, I'm mystified by nonesensical suggestions regarding "classical or jazz" specific gear, as that assumes other forms of music are somehow less polite and require some meatier form of support. The slam of Mahler is just as intense as the slam of dubstep, and your system's limits will be revealed in either case. Do we suggest nobody touch the volume knob? It would be more apt to suggest gear based on the question, "do you always listen at quiet, discreet, mellow, or apologetic levels so as not to wake the baby or incite passion, tawdry displays of senseless emotion, or, dare I say, DANCING?" Then a mini watt tube amp or tiny speakers are for you (and I refuse to be your friend). BALDERDASH! Jazz can be insanely dynamic, acoustic pianos can really test a speaker's strengths, and classical can be as ballsy as Norwegian Death Metal, although perhaps not as tedious and adoreable. Those Norwegians!
I'm in the "SS preamp to tube amp" camp as I want the signal to be as pure as a virgin's heartstrings (!) before it's filled with 2nd order grease by my amp. Plus, most power amps have larger and therefore more engaging tube glow than many preamps where you can't even see the damn tubes! Now I'm all upset! *sigh*...OK...it's OK...whew...