good value for the money
I have previously owned the 502 and 504 models. Both lasted 5000 hours of use (this is at a cost of under five cents per hour) before they became tempermental. They had senior moments when I selected last memory location and they played some random start point instead. The 504 also got very picky about what It would and would not play. This is the "bad disk" and stopping for a few minutes then playing some material five or ten minutes further on.

Anyway, this is good value for the money which is why I have bought two more in the series. The 506 is new and so does not have senior moments or picky taste in what it plays.

It is VERY important to read the manual through several times and make notes in the margin before turning on the unit. If you are not using the unit in the default settings mode you could have degraded performance. In my case with only two stereo speakers I had to use the settings menu to turn off several of the audio features including surround sound, subwoofer, and center speaker.

As a quick test, I tried playing about six DVDs that the 504 either refused to play or gagged on in the new 506. All of them played flawlessly on the 506. I have no doubts that the 506 will meet the needs of ordinary people for watching their DVDs in a pleasant and nonirritating way.

Onkyo DV-SP506
I purchased this player primarily to play SACD and DVD audio discs and I have been very pleased with it's performance thus far. It has a full feature set and a simple, yet intuitive menu. I have also had the opportunity to watch a handful of DVDs and have found its performance (sound, picture, scaling, etc.) to be on par with that of the more expensive offerings from Denon and others at a more pallatable price point. Some of these more expensive units offer a broader feature set and nicer remote, but honestly,I have no "real" complaints because as stated above, it's primary role in my ststem is for multichannel music playback. Since Blu-ray players have become the defacto standard for movies these days, there are many affordable options now if DVDs and blu-ray discs are your only media concerns. However, I definitely recommend this product for those looking for a player that supports multichannel music discs and you are not looking to break the bank in the process.

Great sound, needs frmware update.
Edit: It is April 1, 2010 and Onkyo has not released a firmware update for this unit. It's a shame that Onkyo is not interested in fixing the problems with this player.

I bought the Onkyo SP-506 primarily for multi-channel hi resolution audio listening using the 5.1 analog outputs. The 506 employs 3 high end Burr-Brown 1796 DAC's (3 stereo DAC's to handle 6 channel audio, 5 + .1) and really sounds fantastic using multi-channel DVD-A or SACD. There are some issues however that keep it from being a truly stellar unit.

Pros:

- Incredible multi-channel audio sound, especially when taking advantage of the BB1796 analog capability.

- Ability to covert and transfer through HDMI, multichannel DSD to 176.4 kHz PCM.

Cons:

- Price. Looks like inflation really kicked in with these units. The price is now 0 more than I paid a short while ago.

- No available firmware updates. I have many devices from various manufacturers that are supported very well with down-loadable firmware updates. There hasn't been a single update made available for download.

- Drive noise. There is a definite audible whirring sound with the unit. Can't be certain it affects all units, but mine is a bit annoying. An audiophile would be peeved.

- Fast forward, fast reverse, and pause buttons do not function while playing DVD-A discs that have an interactive menu.

-Cannot adjust video picture controls while watching a presentation. Must stop playback and enter the setup menu to do this. No on-the-fly which is not great IMO. Much cheaper units even have this ability.

Wishlist:

- Better analog control such as adding "channel level" and "crossover setpoint" adjustment

Fortunately because the sound is so good, it's a keeper for me. I'll have to live with the broken features until Onkyo releases an update.

Great Multi-Format Player for the Price
I was on the fence with this player, I narrowed my choices down to this Onkyo and a Pioneer Elite DV-58AV and ended up going with the Onkyo since it was lower cost and new (I could only find refurbished DV-58AV's at the time for 0 more). I'm happy to say I was not disappointed with this player. It passes DSD bitstream over HDMI straight to my Onkyo Receiver (TX-SR706) and the sound is as good as my old Sony DVP-S9000ES for SACD's, passing DSD to a my receiver was key to this though as I found that using it's internal DAC's for SACD wasn't as good as Sony ES SACD player. DVD-Audio also sounds very good when using this unit's internal DAC's using the Analog 5.1 channel out, in this case it did sound better than having it pass over HDMI like the SACD's. I actually bought this to only play SACD's & DVD-Audio primarily, which it does very well (especially at this price) so I was pleasantly surprised when I played a DVD in it, the up-conversion is done very well, it even does a better job of up-converting than my BluRay player (Sony BDP-S500) with standard DVD's. If you're looking for a great up-converting DVD player you can't go wrong, If you want to use this as a SACD player I have to say I was impressed when sending the DSD steam to the receiver, as for DVD-Audio I really don't have another player to compare it to, it sound good, not as good as it does with SACD's but much better than the CD versions of the albums. To sum up, this is a great multi-format player for the price, I think the majority of listeners & movie goers would be impressed with the quality and performance.

Excellent Unit
The player is super with all the HDMI connections. Excellent performance and resolution of non-HDMI DVDs as well.