Hi Christian, welcome to the forum!
The Akai deck you're looking at is a consumer model and doesn't offer the benefits typical of decks used for mixdown.
For starters, this deck is what's called a 'quarter track' deck, where the recorded program occupies two tracks that each take up about one quarter of the usable tape width. The kinds of decks used for mixdown are called 'half track' decks, where the L and R audio track each occupy half of the usable tape width.
Also, the highest speed that this deck operates at is 7.5 inches per second. Higher quality, "professional" decks run at 15 ips (or sometimes 30 ips in nicer studios).
$25 isn't a bad price, but you can do better for just a little more. For example, this Tascam 22-2 would make a good starter mixdown deck, and costs $125:
Link
A better machine, the Tascam 32, shows up on Craigslist and eBay around the $150-$500 range. Here's one on eBay for example:
link
For just a couple hundred dollars you will find another deck that's orders of magnitude better, with more spare parts and a better user community.
Hope that helps!
Jeff
