As I understand it, the sync on the 880 doesn't work all that well; however it's been rated as quite good, but the 660 is supposed to have better sideband quality. There is a groups.io reflector for this radio - it's gone rather quiet lately but (apart from anyone here) you might find some additional comments .....
Tecsun PL-880 receiver discussion.
groups.io
There have been any number of reviews on this radio, and it would be wise to check them out.
Now that you're talking about the radio-what about the antenna? Our Receive Antennas below 30 Mhz forum is for that, but keep in mind that a good radio won't perform well without a good antenna...
For all topics related to receive antennas used on HF, MW, LW, etc. For transmit antennas use the Amateur Radio Antennas forum.
forums.radioreference.com
Be as specific as you can about your situation - can you put something outside? How much room do you have? Are you a tinkerer who knows how to solder? These are all important considerations
Mike