Good day everyone, I'm sorry for google translation of my impressions written down on polish forum :
Sony - a Japanese brand, infamous for its cool, strictly corporate approach to customers, and yet I have always had a soft spot for it. I have always associated it with high-quality workmanship and above-average durability. The times of smartphones and PS3 consoles have severely damaged this opinion, but in general, you can still count on solid products.
Here, however, I went back in time quite a lot because the Sony MDR-CD3000 is a return to the 90s. Exactly 1991 was the year in which Sony released this model to the market, and it ended production only in 2004. My fascination with Sony headphones began with the accidentally purchased MDR-CD770. Back then, Sennheiser HD650 reigned supreme on my desk. These were two completely different schools of play. Sennheiser was calm and dignified and danced my favorite pieces and the CD770 was the energy needed to wake up from lethargy: D As popular music was dominant, I used Soniak more often. I do not know why I sold them to this day, or maybe just to return to those moments with nostalgia and then try something from the higher shelf, of course for those times
It started with an innocent borrowing of headphones from a nice friend

With the first track, you can immediately hear the specific Sony tuning for this period. A balanced reference - that's how I hear it. Pretty bright, full and direct sound. It is quite sharp, there is a strong claw, a huge amount of details and a high emphasis on achieving the highest technical level, but not at the expense of a soulless, cold, only analytical message. At the same time, you can feel the flowing warmth, analogical in my understanding.
The execution here, unfortunately, does not suit me at all for the flagship of these years. I understand that Sony, after the unsuccessful sale of the MDR-R10, wanted to make up for the losses as soon as possible with the cost of materials, but here in my opinion they went too far, which can be seen with the next lower models, which were simply much better made. The mentioned CD770 model is a masterpiece. Just like plastic, rubber and silicone, but of such quality that these headphones still look like new today.
I was lucky that I found a super-well-kept copy, which additionally underwent professional restoration at a well-known Warsaw foreman

Very good quality 3.5mm jack sockets were inserted, a completely new elastic leather band was sewn and the entire headband was completely renewed by a new filling with a hemming.
All I did was strengthen the place from the inside where the plastic is always cracking, right next to the headband. I bought leather pads, which are worth recommending because I have not met such a performance from Aliexpres in person:
https://pl.aliexpress.com/item/4000327010322.html They were made of two types of natural leather. The part that is pulled over the headphones and adjoins the ears directly is made of very thin, probably calf leather. Inside the pads there is another, much harder, stiffer one with a smoother texture. The filling itself is full of memory foam. The height of the pads is appropriate because they were more or less so low in the original. The set also includes sponge inserts that I have not tested yet. Generally very pleasant to use, it is difficult to put them on because they fit tightly and natural leather is not as stretchy as synthetic leather, but I suspect that now it is calm for the next 20 years

It is also worth noting that the CD300 completely hates velor or higher pads .
The visible cable was made from the Canare StarQuad l-4e5c guide, because the pure copper somehow sounded good with them, not only audibly but also visually. A 3.5mm jack plug with a 6.3mm screw-on adapter as it was in the original

There is no point in going into balance because these headphones will play out of everything.