Maybe $100 max if you use all the suggested mods in this thread, more if you're tube rolling. Just some caps and a few resistors and your away to the races to better sound. I find the best mod and it's free is to remove those 2 caps then do the rest if you're so encouraged by the first mod. The MP301 is a tweakers dream.

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¿lɐɯɹou ǝq ʎɥʍ

Well then, that's a pretty minimal investment in order to realize significant gains, and have fun with it as well. I'll probably get another one at some point and follow the advise.

Keep in mind that the 301 has a wide sound stage. If your headphones are tuned for a wide soundstage its going to sound distant and the mids will suffer. My headphones that shine on the 301 are the LCD-2, HE-500, and sein600. What do these all have in common? They are closed in. My lcd-2 crushes my lcd-3 on the 301 for this reason.

[Keep in mind that the 301 has a wide sound stage. If your headphones are tuned for a wide soundstage its going to sound distant and the mids will suffer. My headphones that shine on the 301 are the LCD-2, HE-500, and sein600. What do these all have in common? They are closed in. My lcd-2 crushes my lcd-3 on the 301 for this reason.]

Ive got lots to learn about amps and headphones. The MZ2 was really interesting, but ultimately not a keeper,almost exclusively because of the bass.The midrange was startling though. Ive got a new amp and headphones coming, Ill keep listening and learning. The 301 is a good benchmark.

I had one of the main electrolytic caps fail( dont know why) so have my unit disassembled at the moment.

I have been thinking about some other mods. Note I am not a techie guy, and understand only the basics.
1)Gary says the transformer is of good quality? and is potted inside the housing. So thats probably a no go. But the chokes are accessible.Gary says those are custom made as well, but it would be nice to try and find some alternatives.( The whole thing is only 450.00) There's got to be some way of improving the power supply.
2) The input wires are bundled with power leads from the chokes. I am going to reroute one set of inputs along the side of the chasiss. Take them out of the bundle and go straight to the input on the main board. I dont like the VC anyway so Im going to bypass the VC and the input switch, and the plastic snap on connectors, reroute the grounds and use new high quality wire. ( may need some resistors to lower the gain, then use the VC on my D2 which has been upgraded, or I have a battery powered LDR VC which is the best Ive heard( or not heard:)
3) I would like to change out the IEC plug( not sure about sizing) and install some new input jacks while the wire is being upgraded.
4) I dont need the speaker outs so Im going to remove the wiring for those, and take that signal out of the equation.

That's all I can think of for the moment, if any one has any other ideas, or think mine are crazy fire away.

I replaced the cheap blue 250V 150uf caps with higher quality Panasonic's (same values) and it did wonders for imaging/higher freq extension.

Thanks Steve, Ill keep that in mind.

Peter,

The jupiters are finally starting to settle in on my mp-d1, very impressed. I only replaced the .22uf caps, do you think replacing the 2,2uf is worth it? It would be an additional $120 for the HT beeswax

I always felt somehing was lost or "traded" with the higher capacitance filter capacitors. My least favriote mod. Sure we have more bass and less noise but I felt myself being bothered by something I coukdnt put my finger on. Had some Mdorf supremes .22uf laying around not being used and decided to install them as crossovers on the 450v 470uf caps. I simply extened the leads with some wire and soldered them to the undersides of the caps. Harshness!!! Its gone, sound is smooth and im getting sucked back into the music like I used to. This essentially lowers the ESR of the two caps.



The cap in the rear is an easy fit, wires go under choke transformer. The other cap is a bit tougher and barely fits underneath the daughterboard.

Good job Steve. If we keep bashing away at the 301 well end up with something eventually. That those kind of mods can have an impact reinforces to me that the whole power supply is running on a shoestring. For eg I havnt done the calculation but Im pretty sure that the input choke is way too small. Also the quality of the rectifier is probably pretty questionable. It would be nice to have a better quality conversion. But theres very little room for those things.
I am in contact with Cinnemag at the moment about some custom output transformers. That has the potential of being a huge upgrade.

Thx brooster, I do like the idea of replacing the rectifier if there is a higher quality piece to be had, any good finds?

Sure we could stick a schottky in there. 85USD

The topology of the output stage on the 301 is Ultralinear, A/B and uses feedback.
Im not sure what Gary is talking about in his description of the 301.
I guess thats CH-FI. In the end its all about smoke and mirrors.