klipsh scala speakers

I personally don’t care for them. You can really hear the cabinet in them and they have no bass. He would need subs for sure. 
A number of people like them so demo before you buy as they are pretty different from modern speakers. I like the Cornwall iv or even forte better due to much better bass. 

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.