I noticed that some pages back people were discussing the audio hardware difference between ZX300 and ZX507.
At first I was under the impression that they were identical, but after a bit of research I found otherwise (actually my real job field is also research and analytics).
There are a few key differences that will affect the sound between ZX300 and ZX507, these are all mentioned on Sony's site and interviews with the engineer's.
1. The gold color FT-Cap used in ZX507 is actually the same used throughout the Sony DMP-Z1, while the ZX300/WM1A/Z all use the blue FT-Cap.
-I'm not saying the gold is better, I'm just saying it is likely tuned to sound different to the blue version. This only affects the balanced output on the ZX507.
2. The ZX507 has double the capacitance for the single ended power supply, from 200uF on ZX300 to 400uF on ZX507, this only affects single ended but will result in much better single ended sound. WM1A/Z still have the ZX507 beat in this regard as they use FT-Caps for single ended rather than the Pos-Caps that ZX507 and ZX300 use. (ZX507 on left, ZX300 on right)
3. The ZX507 uses a thick CNC milled copper block for the grounding and total shielding of digital section (a first for Walkmans actually).
ZX300/WM1A/Z only use thin copper sheet metal over the digital section and do not fully encase it, just rest on top. This actually means the grounding and shielding of the ZX507 is above even that of the WM1A, but not the WM1Z obviously as it's chassis is grounding heaven being made entirely of copper.
4. Solder, Sony had been using pure 99.99% Tin solder since ZX2, but improved that to Tin + Gold solder for the ZX507 and A100, and will use this for future Walkmans.
My all time favorite wire is actually Mundorf Silver Gold (1%), don't underestimate a bit of gold in the audio chain.
5. FPGA. All walkmans in the ZX series have used an FPGA since ZX2, this means Sony can easily tune the sound of each model to harmonize well with and take most advantage of it's audio circuitry, also means the ZX507 is bound to be tuned slightly differently to match it's change in audio hardware.
Just a fun fact if you are a science buff: The silver model of ZX507/ZX300 will actually perform very slightly better than the black, this is because the silver aluminum finish will have a lower electrical resistance compared to the anodized black model, this will affect the grounding performance of the chassis. This is also the reason Sony gold plates copper parts, to stop the copper oxidizing which increases the electrical resistance (oxidation can also look ugly).
Now just to be clear, some of these changes will be barely audible, although some people do have a knack for hearing minute changes.
But my point is that when you change this many different aspects of the device, it all adds up. I haven't heard the ZX300 and ZX507, but some people have said ZX507 sounds better than WM1A, others have said it sounds similar to ZX300. So as always, YMMV.
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I've noticed you have gotten good at it yourself though!
