Here's what happened 
Got my hands on a NAD 114 for 55€. Fully working, even sounded alright, no crackling pots and just a slight noise on full volume in speakers and headphones.
Fully original condition. But the transformer was buzzing, mechanical vibration and like sizzling sparkish sound in it. Enough to hear from few meters away in a quiet room. Loose sitting cover didn't do any favours to it. So I thought I change the transformer. Ordered this one: MCFE030/25, 30VA, 2 X 25V encapsulated toroidal for 32€. 81mm in diameter, bit too big but made it work. Had to grind junk out of the PCB I don't mind.
Replaced PSU and preamp circuit caps on the way. It sure is quiet now no mechanical buzz and just a very very light hiss in tweeters on full volume, got to get close to hear it. With headphones cant even tell if the volume is on zero or 100%. One thing to do still, should probably heatsink the LM337 regulator as it runs a bit hot.
Sounds lovely together with the Pioneer M-10X and sounds very very similar to 106. Not sure I could tell the difference between two.
114 seems a tad bit less noisy, but it's marginal. I like the look of the 114 - metal knobs would be nice.
One thing to say. The NAD 106 was so easy to work on. Just remove the top and bottom cover and there you go. 114 on the other hand is the opposite. Have to pull it fully apart to to replace caps - no removable bottom plate. PCB is partly held by annoying plastic clips, have to undo the back and front plate, lot of screws that could easily be all the same but not, etc.
Anyway great preamps, plenty of mileage in these things still.
Got my hands on a NAD 114 for 55€. Fully working, even sounded alright, no crackling pots and just a slight noise on full volume in speakers and headphones.
Fully original condition. But the transformer was buzzing, mechanical vibration and like sizzling sparkish sound in it. Enough to hear from few meters away in a quiet room. Loose sitting cover didn't do any favours to it. So I thought I change the transformer. Ordered this one: MCFE030/25, 30VA, 2 X 25V encapsulated toroidal for 32€. 81mm in diameter, bit too big but made it work. Had to grind junk out of the PCB
I don't mind. Replaced PSU and preamp circuit caps on the way. It sure is quiet now no mechanical buzz and just a very very light hiss in tweeters on full volume, got to get close to hear it. With headphones cant even tell if the volume is on zero or 100%. One thing to do still, should probably heatsink the LM337 regulator as it runs a bit hot.
Sounds lovely together with the Pioneer M-10X and sounds very very similar to 106. Not sure I could tell the difference between two.
114 seems a tad bit less noisy, but it's marginal. I like the look of the 114 - metal knobs would be nice.
One thing to say. The NAD 106 was so easy to work on. Just remove the top and bottom cover and there you go. 114 on the other hand is the opposite. Have to pull it fully apart to to replace caps - no removable bottom plate. PCB is partly held by annoying plastic clips, have to undo the back and front plate, lot of screws that could easily be all the same but not, etc.
Anyway great preamps, plenty of mileage in these things still.