Have I Hit The Point Of Diminishing Returns?

System ... Musical Fidelity Nu Vista CD, Bat VK-3i Preamp, Musical Fidelity A300cr power amp, Magnum Dynalab MD-102 Tuner, B&W N804 speakers, Cardas Golden Reference speaker (bi-wire) and ICs. I realize my rig is a bit dated, but it sounds great. If I were to upgrade, how much better could it get? Have I hit the point of diminishing returns where a lot more $$ gets only a small % increase in sound quality? If not, what component would you suggest upgrading and why? Thanks to all.
Thanks Rlb61.
I surfed the web last night again to see if I could get some dope on this amp but it was hard to find anything. So I'm still guessing at the input power transformer size.
Looking at the A300 amp profile I'm thinking it's a 1KVA transformer.
if so, then, I calculate something like 11Amps/channel. Further, you have the plus & minus rails so each rail gets 5.5Amps. That's a very low amount of current to make a floor-standing B&W really sing. You'll get pretty OK sonics using such an amp but the speaker is capable of much more which could be unleashed by using an amp that has a 2KVA or higher power transformer (which would double the current output). Now you are talking of an amp that it pretty tall - like 10" tall - and much more expensive.
Class-D amps get you high current in a smaller chassis & for fairly reasonable price.
Unfortunately, that's the nature of the (B&W) beast.

one serious thing to consider is to passive dual-amp (I'm not using the term bi-amp as bi-amping implies xternal x-over) using a high-current, low-impedance capable, reasonably priced class-D amp to drive the bass (you've biwired them so they have 2 pairs of binding posts). Then, 225W/ch of the A300CR should be plenty for the highs & mids. FWIW.
Bombaywalla - Thank you so much for your effort and advice. It is appreciated greatly.
You can make price-wise lateral moves and maybe find a sound that really is quite nice. It is all about synergy. For instance I run a Rogue Cronus Magnum with Lessloss original power cord, Tekton Lore speakers fed by Clear Day shotgun speaker cable,DAC is the Metrum Octave with Tel Wire power cord, Digital cable is the Stereo Vox Ultra II,and cable from the DAC to Rogue is Audience AU24. All power is plugged into a BPT power strip fed by Lessloss original and Audience AR1P wall power conditioner into a Furutech outlet.It has taken several years to find the synergy in these components. Except for the Tel Wire power cord most of these items are reasonably price new or used on Audiogon

Sounds super at all volume levels and plays loud.
+1 Doug Schroeder.

Yes, you past the point of diminishing returns as soon as you go past your first boombox.
I disagree! Once one experience what's available, they will upgrade or change. Sometimes it's good NOT to know what's available.
The laws of diminishing returns hit early and hard, just as in any other hobby. A $10,000 watch is not 1000 times better than a $10 watch. Same goes for audio gear.
Nobody buy $10,000 watches to keep time but an accessory or enjoys collecting them. Same with cars ... The equivalent in audio is always on a journey and never reaching a destination ... enjoy cycling through gear.

Bottom line is if you are happy with you system, just enjoy the music and stop worrying about upgrading.
Joecasey, do you understand what the law of diminishing returns means? I never said that spending more money would not improve a system sonically, most times it does. However, it is not on a linear scale. A $20,000 system does not sound twice as good as a $10,000 system. It's more of a logarithmic scale, which would indicate that there is diminishing returns on money spent.

I have listened to many systems priced from $2,000 to $500,000. Yes, the $500,000 system was great, but it wasn't twice as good as the $2,000 system. It could have been....if the $2,000 system was defective, or poorly assembled. Obviously, YMMV.