Have I Hit The Point Of Diminishing Returns?

What John says is true, but if a particular switch or upgrade is worth it to you then that is all that matters.

Charles - yes, I think you're right. I was curious as to price/performance ratio after one gets to a certain point in the "journey." Perhaps I have a case of "upgrade-itis," but it is dissipating quickly. After asking myself the question you posed, I couldn't come up with a rational answer. I think that, in and of itself, speaks volumes.

Rlb61,
You're happy with your sound. If you read many posts on this site you'll realize some folks never seem to reach that point. Thus the constant and frustrating "upgrade" pathway.I'm not suggesting nothing can be improved upon, but what's being improved? Clear objectives would need to be solidly determined/defined.

A thought to consider: Rather than fixing what doesn't seem to be broken (i.e., "upgrading"), consider adding a high quality pair of headphones and a headphone amplifier. I find having both speakers and headphones available (Stax electrostatics, in my case) to be nicely complementary. For several reasons:

1)Having two (very different) sonic perspectives adds interest from a musical standpoint.

2)Headphone listening takes the room, the speakers, the power amp, and most of the preamp circuitry out of the picture (assuming the headphone amp is connected to the preamp's tape outputs), which can be helpful in diagnosing system issues and/or providing reassurance when audiophilia nervosa strikes.

3)Headphones, of course, can make it possible to listen when listening via speakers would disturb others in the household.

Just a thought. Regards,
-- Al

07-27-14: Rlb61
Interesting views. My power amp is 225 wpc dual mono, so I THINK it's powerful enough, but I could be wrong.

For B&W speakers it's not only about Watts/ch - it's about how much current the amplifier can provide to this particular brand of speakers. B&W are well-known to love high-current amplifiers.
I searched hard on the internet to find some A300CR specs but all I could find was A300 & A3CR specs. In particular I was trying to back-calculate the size of the A300CR transformer & the amount of current it could provide.
B&W speakers have a terrible impedance & phase curve in the low freq which gives most amps a lot of trouble because the amp is forced to output a lot more current than what the impedance-only curve informs you.
If you look at purely watts, you might be OK but you probably are shy on output current & that might be limiting you. FWIW.