I purchased this modified unit in May 2025 from the person who performed the modifications. The operation has been confirmed and there are no issues. This is being sold to organize my equipment. Please check the photos for the appearance of the unit and make your judgment. ※Notes: Please note that this item is also listed on other flea market sites, so it may be sold out. Below is the description from the seller on Mercari who performed the modifications: ------------------------------------------------ This is the result of modifications I arrived at after over a year of work. I started by collecting vintage to current models from all eras, recording the parts counts, and comparing the sounds. After repeated trial and error, I achieved a three-dimensional sound, depth, and thickness that surpasses vintage, while maintaining the energy and guts of the current model with TRUE BYPASS, without touching any circuits other than the op-amp. ・Used 7 SD-9s, constantly comparing them through trial and error. ・Tested over 15 types of solder, all of which are difficult or impossible to obtain. ・Only used op-amps from 1980 or 1981. ・Tested 6 types of wires, from standard to vintage. ・Did not use op-amp sockets as they degrade the low frequencies. ・Used early models as much as possible. As a result, I am selling one of the 7 units that remained. The solder used is Ersin Multicore SAVBIT, believed to be from the 1940s. The alloy ratio is sn50 / pb48 / cu1.5 / anti0.5 It features a unique mid-range. 【Modifications for Sound Quality Improvement】 (1) Replaced the op-amp with a 1981 JRC4558D glossy version. (2) Replaced the jacks with Puretone jacks. (3) All solder points were replaced with vintage solder. ※Due to work constraints, the wires were replaced with domestic AWG24 UL1007 standard wires, equivalent to the original. 【Other Changes】 (1) Ultra-high brightness blue LED (2) Knob replacement (potentiometers also replaced for this reason) ------------------------------------------------ Remarks: This unit can also be used with a 9V battery inside the enclosure.