The instructions are still on the Sumico web site under "REL set up made simple".
Here is the first page:
REL Set-Up Made Simple
RELs are not traditional subwoofers, but true sub-bass systems. A REL is designed to augment the performance of full range speaker systems, to provide linear response down to below 12 Hz (Studio III, -6 dB down at 9 Hz). Therefore, for the moment, set aside everything youve been taught about subwoofers and how they are integrated into a stereo or theater system. RELs set-up and position differently than other subwoofers. A REL will take advantage of physics and room acoustics to provide deep pressurization as no other sub-woofer can. Its important that you bring to the set-up process a willingness to do things a little differently in order to obtain these superior results. The end result of your labors will be an utterly seamless integration of true deep bass to a sound system, regardless of the main speakers low bass capability.
Two Things Before You Begin
It is helpful to know that you will almost always connect the REL to the input on the rear panel labeled Hi Level. This connection is made using the supplied 34 10 (10 meters) cable, the bare leads of which connect to the speaker output terminals of the power amplifier. The easy and foolproof connection at the REL is done with a Neutrik Speakon connector. The purpose of connecting to the speaker output terminals is one of the unique secrets of RELs success. By connecting to the high level input on the REL from the amplifier, you build forward the sonic signature of your main system, including the tonal balance and timing cues of the entire electronics chain. In this way, the REL is fed the exact signal that is fed to the main speakers.
When possible, the REL should be placed in one of the corners behind the speakers. Remember, we are dealing with true LOW bass pressurization with RELs, not the mid-bass that most competitors settle for. Low bass pressurization below 40Hz is best derived from corner placement, where the most linear and efficient low bass can be produced.
Basic set-up should take no more than ten to fifteen minutes to accomplish once connected.
Connecting
High-level connection, using the enclosed cable with the Neutrik Speakon connector, is always the first choice. By connecting to the amplifiers speaker outputs the sonic signature of the entire amplification chain is folded into the signal for the sub, thereby keeping timing and timbre cues consistent. In other words, the signal sent to the REL is exactly the same signal sent to the speakers, allowing for seamless integration. This connection can be made without affecting the performance of the amplifier because the subs amplifier input impedance is 100,000 ohms. This scheme also avoids adding any detrimental effects by not interposing any additional electronics into the amplification chain.
The standard high level hook up procedure is: attach the red wire to the amplifiers right positive speaker output terminal; attach the yellow wire to the amplifiers left positive speaker output terminal; attach the black wire to which ever of the amplifiers ground output terminals is convenient; plug the Speakon connector into the subs high level input.