Your formula is off by a factor of 4. 24 vpp across 8 ohms = 9 watts.
Sorry 'bout that.

But who cares -- is it loud enough or isn't it?

Roy Lewallen, W7EL

Ken Scharf wrote:
I built a small audio power amp to drive my computer
speakers. With one channel driven into 8 ohms the PP
voltage measured at 1khz was 24v before clipping.
With both channels driven it was 20v.

I think the formula for power output was ((vpp/sqr 2)**2)/R
which would give me 36W one channel, and 25w per channel with
both driven.
(not bad for a 2n3055/mj2955 pair running at +- 15 volts)

Is my math correct?