klipsh scala speakers

I've heard a few different La Scala. Every time I liked them they were coupled with Mac valve gear.

Every time I didn't they were powered by SS amps and Line stage preamps.. It just doesn't work.. VERY sensitive to noisy gear and cable routing.. Pay attention to the two.. You'll still be quite LOUD and have a blacker background.. Valves use of different harmonics in the voicing is the reason why.. Just a horn thing to me..
Valves and Horns. Peas and Carrots.30-75 watts.. per rail.. that plenty.

Personally I never heard a bass issue. BUT these were die hard horn guys.. they knew how to set them up. K-Horns.. too.. Good rock and roll speakers.. They were running subs in a couple of the set ups..

Regards

I had the Cornwalls and the Klipshorns in the past. Both had bass but didn't go as deep as you would think they would for their size. I ran a sub with the Khorns.

I have a pair circa ‘86. They sound great on tube gear and are very efficient so they don’t take much to get loud. Bass is super fast but not deep at all. If he wants to shake the house, they are not the speaker for him. Cornwalls have much better bass. 

Try to find your son a large vintage american speaker made before 1981 that will fit his style and volume requirement he will be much happier than any new speaker and you will really like them also.

Klipsch LaScalas are an audio classic.  They are, quite literally, the "Hemi Cuda" of the audio industry.  If he has the physical space and isn't shy with the volume control, they could be a perfect match.
Be aware, however, that the larger Klipsch speakers are unforgiving of "mid-fi" and will unapologetically delivery every wart, speed bump, and grunge in your system.  Their super high efficiency will produce sound pressure levels at approximately 1/32nd (yes, that's ONE thirty second) the power requirement of a typical "lows 90s" medium efficiency speaker.  That being said, my appreciation for Klipsch is not what they'll do a high volume levels but, on the contrary, how they sound at low volume levels.  A LaScala, played at a level just above the threshold of hearing delivers a stunning degree of dynamic range, bandwidth, and "live" presence.
On a critical note, big Klipsch speakers are guilty of the sins of "ommission" and "commission". In other worlds, their "production quality" crossovers cover up a considerable amount of musical information.  And, cabinet and horn resonances create unwanted elements that exaggerate certain frequency ranges, attenunate others, crush imaging and blur focus.  The later is "fixable" thru low tech dampening to horn bodies and cabinets and will dramatically improve musicality whlle reducting listening fatigue (especially at high volume levels).  And, upgrading the crossovers thru simple component substitutions, or replacing the entire crossover assembly with "newer thinking" (if your credit card has a little more room on it) will deliver much improved detail and focus while further increasing (already superb) dynamic range.
The performance in his room can range from C+ to A- depending on his other components, the room itself, and whether or not he has the appetite for some hands on, or professional upgrades.  
I'd get these in a hearbeat of all the stars line up and the elements are in place to get the most from them.