Galion vs Luxman vs Advance Paris vs (anything else)

Re sub brands, I recommend going with Rel.  Although I have been a bass lover for decades, I had never owned a sub.  After hearing so much about Rel, I had purchased a single Serie S/510 3 years ago.  It absolutely transformed my system in ways I never thought possible.  What's even better, because of the way Rel engineers their subs, I got only the good (musicality in spades, dimensionality, scale, tight bass, etc,), and none of the bad (zero boominess, zero woofing, zero "flouncy" bass).

This is not to say other brands can't provide that same level of goodness, but I had one shot to buy a good, musical sub (WAF was not high), and I went with an absolute and never looked back.  I have since bought a second S/510 which completed the soundstage and extended the dynamics even further.

However, having only one S/510 was still amazing and I could have easily maintained my system with only one quite happily (one provided 80% of the scale of having two).

Lastly, if you're going for only a single sub, make sure it's over powered relative to what you need (this is why I went with a S/510 and not a T/9x)... you can always turn down the volume level on the sub if it's too much... but, you can't easily turn up the power if your sub can't pressurize the room adequately. 

Good luck. 

SVS has their micro 3000 sub on sale for $699 right this minute. I'm contemplating a second sub @ at that price. They offer a further discount if you purchase two at the same time. Built in amp and app make tuning to your room a breeze. The only caveat is the sale price is for gloss white. Super happy with my single as I run a 300b SET and the powered bottom end is a godsend. 

@genomeip I have heard very good things about Rel, I will check out your suggestion. Thank you!

@brooklynhifi - deeply appreciate the suggestion as well. I’m going to look at both brands!

@ctlesq Rel's website has a cool feature where you can search for your speakers, and it will tell you the best Rel sub that matches it's performance.  If you don't find your speakers listed,  you can always reach out to Rel directly.   I have done that twice, and each time I had a senior Rel employee call me directly which was quite a nice touch.  I ultimately went against their recommendation due to room considerations and the type of sound I was looking for (they recommended two 1510 Predator subs from their home theater line (what they recommend for all Klipsch Heritage speakers), but I wanted musicality instead and went with the S/510s which was the more expensive option and the better fit for my use case).

Lastly, make sure you have a firm conviction about your intended application before you buy.  For example, if you are leaning primarily on sound quality in a 2 channel system as opposed to only occassional home theater use, Rel's Serie S line is a great choice.  But, if you want super slam for home theater use, and only occasional 2 channel use, I would recommend their HT line instead.  Note their Carbon Special sits in the middle of their S and HT lines and is fully competent with both uses (but that dual utility will cost you significantly).  My S/510s are only at 45% power for 2 channel (>98% of their use case), but I need to turn them up to 100% for home theater use (<2% of their use case).

@ctlesq  Whatever sub you choose make sure it's capable of connecting to 'high level input'. This way the subs (hopefully a stereo pair) will fully benifit from the punchy character and dynamics of the new amp you're going to get!  

Discuss this with SVS tech help live on the phone. 

One last point would be to set crossover somewhere around 50-60 hz. and don't  high pass the speakers. Let the speakers breathe!! Run full signal and let the subs fill in the  low end. 

Your system is good but it will be amazing after these additions. (I will confess that I too have been eyeing the Galion amps.)