The Onkyo is not rated for the 4 ohm sub, but has plenty enough power for it without triggering overload protection. The sub is not vintage, but an 18" B&C pro cinema driver in a DIY cabinet. Power amp is an older Onkyo 7.1 AVR with 7.1 discrete analog inputs, in direct mode, which gives me remote gain control and plenty of clean power for all 7 channels (2x 3-way mains plus sub). Source is analog output of a laptop streaming Amazon Music HD via a wifi booster module located halfway between my house router and the barn. I do not have the wired remote, but I do have and use the Bluetooth dongle-works great for tweaks from the sweet spot. Thanks to Dayton for making this possible on a slim budget! I could also wish for digital ins to bypass the input ADCs, but I'm "complaining" all the way to my no-AC barn-loft lab where I tolerate harsh environmental extremes to revel in the listening experience into the wee hours. Noise is not a problem to my aging ears except for cable noises from some long interconnects, usually manageable through gain structuring. The DSP has performed admirably my only negatives are occasional low level funky noises on startup and a rather underinformative operating manual, especially in the area of program/preset management. I attribute the imaging performance to the inherent temporal fidelity of digital crossovers, the delays I am applying for signal path and group-delay compensation, and close electromechanical matching of left and right driver pairs from tight manufacturing tolerances. It's a work in process, but so far I am thrilled by the sound quality I am obtaining, easily surpassing my Crites-upgraded Klipsch Forte I's, especially in imaging and midrange transparency.
I acquired it to use for mix-and-match experimentation related to my "Silk Purse" project-an attempt to get Cornscala sound quality from vintage high quality PA drivers snagged on the cheap ("sow's ears") from Craigslist. Thought I would chime in with my DSP-408 experience.