The HK would be B stock and is about $430. Any comments? They seem very similar in terms of features, and both have Bass Management which I need.
The Onkyo does support S-Video upsampling which is a small benefit.
Get the HK, it's 7.1 vs 6.1 for the Onkyo. Also the HK has 7.1 pre outs so you can use it as a pre-amp down the road if you want to connect it to a more powerful amplifier. The HK weighs 40lbs vs 27lbs for the Onkyo. Dual power supplies and better amps on the HK. You'll have more power in reserve. HK rates their receivers with ALL channels driven. Onkyo recently had issues where when all channels were driven the power dropped significantly from what was advertised. Not sure if this has be rectified. Plus the HK has the EZset remote which enables you to automatically configure the sound levels for each speaker.
The HK has 3 optical and 3 coaxial inputs and 1opt/1dig output. The Onkyo 3dig in/1out and 1 coax in and no coax out. The HK also adds Logic 7 which compares favorably to Dolby PLII, multichannel bass management, which is different than the Onkyo's bass management. With the Onkyo, you set the crossover for the subwoofer based on the front speakers. With the HK, you can set the crossover for EACH channel, front, center and rear.
HK also has a RS-232 port for firmware updates.
I think its a no brainer to get the HK-325. I really don't think it's a fair comparison, the Onkyo 701 might have been a better test.
You don't mention what speakers you have, but as a general rule, get the H/K, even if it is "B-stock." Much better parts inside, especially the power supply (a real weakness of Onkyo) and it those parts (such as DACs, the DSP, ADCs, and amplifiers that make a difference). The H/K is a bit on the warm side for me, but it at least has a good power supply and can sound realistic, but the Onkyo by comparison simply sounds thin and unconvincing despite a nice set of "features."
You will be much more satisfied with the H/K.
I have compared the HK 325, HK 225,(not a lot of difference between the latter two as far as sound) and Onkyo 701 recenty in my house. I have hooked up the HK's to both Klipsch RB25's and Paradigm Mini Monitors, with the matching center and surrounds for both speaker systems.(Ultimately kept the paradigm Mini's over the Klipsch and the Onkyo 701 over the HK's) I don't think that you could go wrong with either receiver. The HK 325 was probably a tad more powerful than Onkyo 701 (701 claims 100 WPC) so I imagine it would be noticably more powerful than the Onkyo 601. The HK325 had a very rich sound, with a nice mid-range emphasis, but did not sound as detailed as the Onkyo. I found the bass to be a little looser and the highs a tad brighter ( and consequently, sometimes a tad harsh) on the HK 325. The EZ set remote is convenient, but not as accurate as setting your speaker calibration using an actual sound pressure level meter. (Get one at Radio Shack for $29. Get the analog SPL - it works just as well as the digital for $49). The EZ set worked fine on the HK225, but did not work on the HK 325. Also, consider where you are going to mount the reciever. Because of that huge power supply, the HK 325 runs hot! The HK 325 would get too hot in my video cabinet (21" deep, 8" clearance above to the next shelf, 1.5" clearance on either side). When the HK 325 became hot, the remote operation became highly erratic. Also, the remote on the Onkyo is much better. However, I think that both of the receivers you are considering are great values for the features that they offer and you would be happy regardless of which one you chose. Let your ears (and your wallet) guide you to the best choice for you and enjoy the music!