Quick on the heels of the TX-SR674 ($700), Onkyo released the cheaper, step-down TX-SR604 ($500). The two receivers are largely identical on every count but one--the TX-SR674 is capable of upconverting analog signals to HDMI, while the TX-RS604 can upconvert only to component video. That means the dream of running a single cable from your receiver to your TV won't happen with the TX-SR604, although in most cases you'll only need to run a single additional component video cable. The real loss is you won't be able to leave your TV tuned to a single input, which means you'll have to endure a little extra remote fumbling. That aside, the TX-SR604 offers all the features we liked on the TX-SR674--excellent automatic calibration, XM Neural Surround support and solid sound. In other words, if you'd rather have one less cable and a little less hassle, and you aren't on a tight budget, go for the TX-SR674. Otherwise, save the dough and get the TX-SR604. It's that easy. The numerous buttons and controls of the Onkyo TX-SR604 are neatly organized. The A/V receiver boasts standard measurements of 6.8 x 17.1 x 14.8 inches (HWD) and weighs 25.1 pounds. The smallish remote is only partially backlit but accomplishes a lot with a minimum of button clutter. It's a breeze to use. That said, since the receiver will require HDTV owners to change inputs frequently, picking up a good universal remote will help things all around.
The onscreen menus offer myriad setup options, yet we never got in so deep that we lost our way. For a receiver as well-endowed with features as the TX-SR604, everything is exactly where it ought to be, except for one thing: the onscreen menus don't appear over the HDMI. You can either connect another cable (component, S-Video, composite) to navigate through the setup chores or navigate using the LCD display on the receiver--which can look pretty small if you're sitting far away. Yes, the speaker setup and calibration are handled by the Audyssey 2EQ, but you still have to navigate the menus to assign inputs and deal with minutiae (the receiver's factory default HDMI audio is Off, requiring you to search through the menu to activate it). Of course, if you're not using the HDMI output this won't be a problem, but if that's the case, you should probably save some money and opt for the step-down model, the Onkyo TX-SR574.
The Audyssey 2EQ automatic auto-speaker-calibration system is the best ever offered by Onkyo, but it requires the user to run the setup program from three different positions in the room. It's easy enough to do--just plug in the supplied microphone, then respond to the onscreen prompts. After the Audyssey finishes sending test tones, the receiver automatically adjusts the speaker size settings, the subwoofer crossover points, the channel volume level, and the time delay settings for each speaker. The system is accurate, so we'd recommend using it. The Onkyo TX-SR604 is a 7.1-channel receiver that dishes out 90 watts per channel and offers the usual assortment of Dolby Digital, Dolby EX, Pro Logic IIx, DTS, DTS-ES, DTS Neo:6, DTS 96/24, and Neural surround processing modes. There's a total of five A/V inputs with S-Video (including the front panel set), plus three component video and two HDMI inputs. The HDMI connection carries Dolby Digital, DTS, CD, DVD-Audio, and uncompressed PCM audio--as well as high-def video--between the source and the receiver, so you won't need to hook up a digital audio cable. While the TX-SR604 will convert composite and S-Video sources to component video output, it will not do analog-to-HDMI video conversion. Thus, as mentioned above, HDTV owners will need to run component and HDMI cables to their set.
We counted six digital audio inputs (two coaxials and three opticals on the back panel, one optical up front), and one optical digital output. Compatibility with Blu-ray, HD DVD, or SACD/DVD-A players should be guaranteed, thanks to the HDMI inputs and 7.1-channel analog inputs. Like every receiver currently available, it cannot decode the new highest-resolution soundtracks (Dolby TrueHD and DTS-HD Master) on Blu-ray and HD DVD discs, so make sure your high-def disc player can decode these formats internally, if that's important to you. There's also one stereo analog input, plus a tape in/out set for use with a cassette or CD recorder. XM Satellite Radio, including XM's Neural Surround, is available with the addition of an XM Mini Tuner/antenna and a subscription. The RI (Remote Interactive) jack can be used with Onkyo's DS-A1 or DS-A2 iPod docking units. There are also high-quality speaker binding posts for seven amplifier channels. One final note for analog purists: there's no phono jack, so you'll most likely need to invest in an external preamp to enjoy your record collection.