burned cds work great for me.
TDK blanks only, Plextor plexwriter (frickin' fast) and Nero.

 

I have not had problems playing burned CD's in my s2k's stock deck. I am using Adaptec Easy CD Creator as the software. Now the trick is finding the right brand of CDR's. I have tried several and have had the most success with Maxell's Gold CDR's (not platinum). They have played in all of my stereos, at home and in the car. The Platinum ones are a bit newer and hold more (so the box says), but they do not play in some of my stereos, I don't know why. Also make sure you close the session on your disk when recording.

CD-RW's don't play in the stock deck of the S2k, that I have tried.

 

No problem here with burned CD's on the stock head unit....