Hi all, I recently purchased these items from ebay ( Panasonic RQ-SX56, Aiwa PX347) and would like some input especially relating to the Panasonic model. 

 I know these can hardly be called "retro" compared to some much earlier models as they are both from the mid to late 90's. The sound from the Aiwa is excellent to my ears, very loud and clear through my Sony MDR-ZX700 headphones. Cassettes recorded on my Yamaha KX393 sound very good indeed. It appears to be well looked after, either that or it was never used. 

However, despite being in very good outward condition the Panasonic sounds dull and lifeless by comparison. The mids are recessed and highs just not as bright as almost every other media player in my possession. It also lets through a lot of noise/hiss despite NR in on position.The build quality doesn't seem to be up to the same standard as the Aiwa and it also feels very light in the hand. I've cleaned the heads to no avail and wonder if these RX series Panasonics are just pretty to look at but sub-par in the old SQ department. 

Also worth pointing out the S-XBS and Super Bass (respectively) is far too boomy on both models. 

hehe .. i owned both of them few weeks ago ... but they`re hard to repair... so i threw the aiwa to the bin.. i have that pana still, and sold some of that silver/blue thingies @ bay ... they`re ok, but not powerful in sound ....

the "boomy" sound might come from your headphones .. try to use earbuds. i recognized, that my new portapro are more "boomy" than my sennheiser CX 55 earbuds .... my earbuds seem to be more light and clear, but i hear also more defects from a little faulty model. for example, i have a pana player, which sends a little "tic tic tic" noise .... but it disappeared, when i use the portapro... same with my grundig beatboy. with earbuds, i hear some annoying noises, but nothing with portapro...

the main problem with those flatmen is, they`re not easy to repair and have very thin belts... think, thats the reason of low prices..

It may benefit you to try cleaning aand de-magnetizing the units first. You never know how these units were used and in what environment they were kept.

...and like gearwheel stated..try a good pair of headphones

They still look good

i bought the panasonic new when it came out and it was faulty from beginning, warbling sound when walking, and by now batteries dead, grundig beatboy is 100x cooler

the panasonic is not a quality product