Power/Current: How much is realistic?

A low/moderate power tube amp with a really good power supply like Audio Research's VT-80SE would be awesome.  They can be had used for $3500.

To provide some perspective on this I did a calculation of maximum SPL (sound pressure level) at the listening position based on the following assumptions:

-- Amplifier power 600 watts, corresponding to the upper limit of ML’s recommendation for this speaker.

-- Sensitivity 5 db less than specified, because Stereophile measured the sensitivity of the 13A’s big brother, the 15A, as being 5 db less than specified. That amounts to 86 db/2.83 volts/1 meter, which for the speaker’s 4 ohm nominal impedance corresponds to 83 db/1 watt/1 meter. (Stereophile found the impedance specs of the 15A to be accurate, btw, so I assume that the similar corresponding specs of the 13A, namely 4 ohms nominal and 0.7 ohms at 20 kHz, are also accurate).

-- A listening distance of 3 meters.

-- An assumption that at the 3 meter distance the sound pressure level will have fallen off by 3 db per doubling of distance relative to the 1 meter figure, given that this is mainly a planar speaker. (That figure would be 6 db per doubling of distance for a box-type speaker).

The result is a maximum SPL at the listening position of 109 db, which is certainly enough volume for most of us, even on the brief dynamic peaks of well engineered minimally compressed classical symphonic recordings for which brief peaks can be vastly louder than average volumes.

Going down to 300 watts would reduce that to 106 db. Going down to 150 watts would reduce it to 103 db.

Also, keep in mind in considering various amplifiers that their 4 ohm power rating is what matters, not their 8 ohm power rating.

Also, given that like most electrostatics the impedance of the speaker descends to very low values in the upper treble region solid state amps (having high damping factors and correspondingly having near zero output impedances) will produce greater emphasis of that part of the spectrum than tube amps (which of course have relatively low damping factors and correspondingly have relatively high output impedances). Which is better comes down to individual preference, IMO, although of course high powered high quality tube amps don’t usually come cheaply :-)

Hope that helps. Good luck,

-- Al

my mcintosh mc602's manual says it's current is 150 amperes per chanell. is this true??? if it is, where doe's my amp stand with other's??

Was also considering AR tube end Personally never heard with M/L 
Also had AR Pre Ls25m2 with ss amp.Looking at options, but my ears will decide. 
Thanks Al for some insight
Mike

@g_nakamoto, amplifier current ratings are among the most useless and misleading of specs.  They usually represent how much current the amp can put into a dead short (i.e., zero ohms) for some unspecified miniscule fraction of a second.  And in some cases they may even correspond to that capability as measured at the output of the amp's power supply, not even at the output of the amp itself.

See the following thread:

https://forum.audiogon.com/discussions/current-limit-onset-definition

Regards,
-- Al