I own a Super Tjoeb 4000 with 192 kHz/24 bits upsampling. I use it in a headphone setup with a Meier Audio Corda Prehead headphone amplifier. If you intend on buying a Njoe Tjoeb with upsampling card, be prepared for a long "burn-in" of the player. My player still sounds a bit aggressive and sharp in the treble after more than 200 hours playtime. That is supposed to smooth out according to other owners. And then I even use it with the smooth sounding Sennheiser HD 650 headphones with Equinox replacement cable.
If you buy a Njoe Tjoeb you also have the opportunity to roll different tubes. So far, Mullard E88CC and Philips E188CC SQ sounded best in my system. I have read that Perreaux is smooth sounding, so it should match well with Njoe Tjoeb.
Even though my Tjoeb is almost new, it still bests my modified Marantz CD6000 OSE LE player. Huge 3D soundstage, layered midrange with REAL voices, impeccable rhythm and pacing. The only weakness is the slight lack of impact and slam in the bass, even though bass is far from lacking with HD 650 headphones. Tube rolling also changes the sound fairly much. The stock tubes, Jan/Philips Military NOS tubes are somewhat grainy, two dimensional and lack bass weight. Midrange is really sweet with these tubes though.
