Price Paid:  $80.00 from Best Buy

Summary:
I had a hard time deciding which cd player to buy, so I bought both, tried them out, and am going to return the Panasonic tomorrow.
Well first features: Aiwa had all, and Panasonic had none. I can recharge rechargable batteries with Aiwa, adjust how much skip protection i want, it has it's own ac/dc adaptor. The Panasonic didn't come with one, just a car adaptor.
I can resume playback from where I left off with the Aiwa... it's mildly waterresistant, and better battery life depending on playing conditions of course. But the coolest thing is that i can recharge batteries with this thing.
The Panasonic was a car kit model, but I was looking for something in the same price range that sounded the best, and the Aiwa won in that department.

Now for sound. I used a pair of Sony MDR-7506 for audio comparison, which I'm sure you'll find are excellent headphones for your dollar. While the Panasonic can get louder, with the S-XBS enabled it gets kind of distorted the higher you go. The Aiwa couldn't go as loud as the Panasonic (not by much though) but it was clean all the way up, even with DSL turned on. Especially when listening to Tool, which is extremely wide dynamically (many sounds/voices at once) there was little or no distortion.
Also, the Panasonic added a bit of hiss, barely noticable, but still there while the Aiwa was clean but warm. The final cd i tried, Slipknot, sounded so huge and big and massive on the Aiwa, but was only really loud on the Panasonic. The double bass was right there, loud and upfront, without drowning anything else out, while on the Panasonic didn't sound nearly as 'live'. They sounded pretty good, the both of them. They sounded better than a Sony model I tried out earlier. But for being only 10 bucks more, the Aiwa was a much better buy for me.

Strengths:
Water resistant, huge bass sound, 12 and 48 sec anti-shock, recharges batteries!

Weaknesses:
none significant

Similar Products Used:
Panasonic SL-SX282C

Price Paid:  $79.00 from circuit city

Summary:
We are from Circut City and has tested the Aiwa xp-sp911 vs. the sony 40 sec anti shock (d-e451). The Aiwa is water proof one thing, we had to try that with thew sony. the sony went in the bucket, lasted for 5 seconds, then died (we did that at the end of the tests).TEST 1: SOUND. The Aiwa is fairly louder, more colorful, and has 48 sec anti shock. however, the mega bass and groove on the sony sound much better. The groove, however on the Sony distorts the sound a little at any volume. TEST 2: Quality: We banged and threw the Sony and it wouldn't skip. (we taped the door closed). The Aiwa didn't skip either, but it lasted about 10 seconds longer than the Sony and recorved MUCH faster. TEST 3: TALENT: Niether of the CD players skipped while running a half mile, however we like the aiwa esp better because it goes on 48 sec esp, 12 sec esp, and off. the sony is 40 sec, and off (off is really 10 sec esp and wastes battery when you really dont need it.) TEST 4: FEATURES: We also like the Aiwa better because it has digital volume control, however on the sony it has lock but you can change the volume.

THE AIWA WINS!!!!

...FEATURES...

AIWA: 48 sec, 12 sec, off e.a.s.s. (electronic anti shock system)
lock button
resume where last off
repeat one song
repeat all
random
Digital volume
2 step DSL bass boost
twist lock for top
Waterproof
Rechargable (with rechargable batteries)


Sony Features

40 sec and 10 sec esp (electronic shock protection)
2 step bass boost (mega bass and groove) enhances whole sound spectrum (not just bass)
repeat 1, all, random, program** (aiwa dosent have program)
hold button
resume
remote control headphone ready
line out jack
AVLS ( automatic volume limiter system)

Strengths:
High bass, withstands water, bumps and bangs, 48 sec esp.

Weaknesses:
Lacks the high notes.

Similar Products Used:
Sony 40 sec anti shock

Price Paid:  $140.00 from Space Market

Summary:
I liked it, you should buy it!!!! ;)

Price Paid:  $80.00 from best buy

Summary:
none needed

Strengths:
deep bass power, comfortable durable design, water resistant, 46 second anti-shock

Weaknesses:
none so far

Similar Products Used:
another aiwa w/ tuner, panasonic shock wave metal both broke within 2 weeks

Summary:
This CD player incorporates all of the basic controls and design features that one would expect in a CD player of this price range ($79 and Circuit City) and intended use.

Aiwa has done a fantastic job of creating pleasing sound from this player. Base level is selectable between three settings: standard base, emphasized base, strongly emphasized base. There may be better sounding players out there, but my guess is your going to pay substantially more for it. Best of all, the player doesn't skip at all during running and aerobic exercise routines.

The display runs across the top central area of the player and is large enough to easily read. A large indicator allows battery levels to be monitored at all times. Button controls run around the left, bottom, and right side of the display and are made of nice rubberized material. Actuation of the button controls is very nice with good tactile feed back. All controls are easy to read.

The main door is held shut by a large, silver rotating knob. This mechanism works great unless it is accidentally turned. Care must be taken when pulling the CD player in and out of a waist pack so that this knob is not turned. The door opens about 90 degrees allowing sufficiently easy access to the inside of the player. A rubber seal runs all the way around the circumference of the door which should give good protection against rain and splashing water (the player is not water proof). The battery compartment is also located under the main door so they won't come out if the CD player is dropped or get wet in rainy conditions.

Overall, this is an excellent choice for those interested in a robust CD player for use during physical activity.

Strengths:
The XP-SP90 resists skipping during running and aerobic exercise extremely well. Sound quality is very good (almost excellent). The player has nice controls, and good looks. The combined ABS and rubberized construction should prove to be very durable.

Weaknesses:
The CD player is equipped with a rotating door lock mechanism which is somewhat self defeating. The lock works fine unless you accidentally turn it, in which case the door is virtually guaranteed to pop open. Aiwa should have designed the rotating lock as a secondary mechanism to the primary lock. Alternatively, they could have simply made the existing lock significantly harder to turn.

The head set design is the only other weakness I could see in the CD player. Although the head set sounds very good, and is fairly comfortable, the "ergonomic design" leaves something to be desired. To hold the head set in place, Aiwa incorporates "clips" which rest behind each ear (like eyeglass frames). This is combined with a band that wraps around the back of the neck (as opposed to over the head like others). The band sticks out and gets in the way if you want to listen while laying on your back (when performing a bench press, for example), and the special fingers which fit behind the ear to hold the head phones in place aren't as comfortable as a standard head set (which doesn't have them).

Lastly, the head phones have a rubberized surface which doesn't breath very well. Since this surface contacts the ear directly during use, it can be somewhat hotter than the open cell foam design in other head sets.

Similar Products Used:
While shopping for a CD player I also looked at Panasonic's line. I listened to the Panasonic Jogger + CD player and thought that the Aiwa sounded much better. Since I didn't buy the Panasonic, I can't testify to it's skip resistance during exercise.