I did audition 4040-SM and it's not bad (for 8K). Ahuja had two stereo cassette recorders. One was dedicated cassette recorder CTR-100 (IIRC) and 4040-SM with in-built amplifier (seems TO-3 based transistors. Probably 2N3055..just guessing here).No exactly. Most of the tape decks had very good (rugged) mechanisms. But yes, they were not Hi-Fi grade. Except their 4040SM model. I had the opportunity to use one and I found the sound quality exceptional. This particular model (4040SM) was having recording facility and had higher specs compared to the other tape decks which were mono and play-only.
I don't know if they are available today. But if you get the opportunity then please listen to a 4040sm model. My gut feeling is that if they are paired with a good speaker set then you will get good output.
IIRC, they used Elin FLD mechanisms which are quite good and one of the best diy tape mechanisms available till few years ago. I still have some. Elin mech came with normal Philips head (ms).