The resultant tube microphony problems from the amount of gain a (reproducer) tape head needs almost outweighs the notion of thinking different preamplification tech -on such a small scale voltage level- is going to change the line signal markedly (vs. talking a power amp). So many of those (circa) pre-1966-era decks (then ALL TUBE) would, invariably, have; either: a minor buzzing (if the output level pots were turned up beyond a certain point) or the whirring of the motor's AC could always be heard somewhere bleeding into the signal path. When transistors came along, none of those problems (except if the rtr was a budget, self-contained model having its own speakers).
Now, of course, the quality of Solid State varied A LOT at the time; in, how, it was implemented. Many a '70s Japanese decks started using (now obsolete) ICs (the Toshiba 7122 and Sanyo LD3141 equalization stage opamps being total noisy junk parts today) and...in my own experience of (once) having had: a $1500, T-O-T-L Akai GX-400DSS (not "4000"...but "400"; three speed, three motor, Quad, dual capstan, 10 1/2" deck) vs....the semi-pro Magnecord 1024 (from 1965) I have rebuilt and kept: the ten-year-older Magnecord with Germanium transistors sounds five-times better in "presence"/dynamics/stereo separation/etc.
Why(?) --- 1. (obviously) Nortronics heads from the '60s were far better than the Akai "GX" gimmick and, also, because --- 2. a SINGLE channel's preamp card -in the Magnecord- IS BIGGER than the entire playback amp circuit board for a pair of BOTH channels in the Akai(!).
Another thing I found out, from playing around 30 years with this stuff, has been: connecting even the most humble rtr DIRECTLY TO A POWER AMP makes the biggest leap in the "forwardness" of the deck's sound performance and causes a drastic fall of the background noise level. My first experiment of that involved a Teac A-2300 hooked directly to a Dynaco Stereo 400 with A.R. speakers. It was a revelation at the time...the improvement was like having a brand new system.
This kind of arrangement makes one a prisoner to the warts-and-all quality of the source (without any reliance on tone controls) but, it delivers so much more a rewarding experience with a great recording.
