The first point I would make is that your speakers can’t handle more power than the XA30.5 can provide.
John Atkinson’s measurements of your speakers indicate a sensitivity of 85.5 db/2.83 volts/1 meter, close to the published spec. Based on the impedance magnitude and phase angle curves he measured I would consider it to be a 4 ohm speaker **for purposes of SPL (sound pressure level) calculations.**
It should also be noted that the specs for the speaker which are quoted in that review indicate it to be capable of generating a maximum SPL (presumably at 1 meter) of 110 db, and amplifier power of 50 to 150 watts is recommended.
As noted by Three_Easy_Payments in the post just above
measurements of the XA30.5 show it to be capable of providing 195 watts into 4 ohms. It will leave class A operation at considerably lower power levels than that, of course. But I wouldn’t be concerned about that, in part because those high power levels are likely to be required, if at all, only during very brief dynamic peaks in the music, and in part because of what is said about "Leaving Class A" by Nelson Pass in
this excellent paper.For a non-planar non-line source speaker, especially a relatively small bookshelf speaker, putting aside the effects of room reflections SPL will fall off at 6 db per doubling of distance. Using the following calculator ...
https://myhometheater.homestead.com/splcalculator.html ... it can be seen that depending on what assumptions are made about placement and room effects the amp/speaker combination will be able to generate SPLs of between 101.7 and 107.7 db at a listening distance of 10 feet, **if** the speaker would not be overdriven and hence caused to perform in a non-linear manner (or worse) by 195 watts. However given the speaker’s limitations I referred to in the third paragraph of this post I would consider slightly more than 101.7 db at 10 feet to be a practical upper limit.
My perception is that many members here are satisfied with equipment providing maximum SPL capabilities at their listening positions that are in the mid-90s, or even less in some cases. However if one’s listening includes recordings having particularly wide dynamic range (i.e., large **differences** in volume between the loudest notes and the softest notes, such as many classical symphonic recordings), that may not be satisfactory. For example, my listening includes some classical symphonic recordings which have been engineered with minimal or no dynamic compression that can generate 105 db at my 12 foot listening distance, while being listened to at average levels of around 75 db or so.
In any event, given the limitations imposed by the speaker’s power handling capability (which is typical of many bookshelf speakers), if 102 or 103 db or so at a distance of 10 feet is not adequate for your purposes the solution would be to change speakers rather than going to a more powerful amp.
Good luck. Regards,
-- Al
