I did not say REL are junk. They have moved into the HiFi Jewelry market adding things which do nothing for the sound and leaving out things that would.
Phase
=====
To get low end out of a small woofer requires adding EQ to the amplifier which adds phase shift and group delay. Sound has magnitude and phase. This is why an out of phase pair of mains sounds the way it does. The amplitude is the same, but the phase is 180° out. The VECTOR sum is zero except for driver and room anomalies. So to integrate a sub, one needs both level and phase controls for the best VECTOR sum. A 180° polarity inversion is the equivalent of moving the sub ≈14 feet @ 40Hz. And a different distance for every other frequency.
Note that a phase control is not a perfect solution, it's just that it's next to hopeless without it.
See http://www.ielogical.com/Audio/SubTerrBlues.php for further explanation.
Tube Amps
=========
The REL instructions are either written for or by someone with ZERO understanding of output transformers.
Google stereophile phase in Images. Notice how the impedance rises in the low end of most speakers. With an output transformer, when the load impedance rises, SO DOES THE OUTPUT VOLTAGE. Since the REL SpeakOn input is high impedance, the sub output will increase due to the increased voltage even though the amplifier input signal does not change in level.
For the gazillionth time, roll the low end from the mains with a simple 6db/oct passive xover about ½ to 1 octave above the mains -db frequency and drive a sub with multiple XO slopes, phase and polarity controls into the LINE input.
Follow the interface guidelines under Setup at http://www.ielogical.com/Audio/SubTerrBlues.php.
There are links to model your room, main and sub placement. REW https://www.roomeqwizard.com/ also has good modelling.
Phase
=====
To get low end out of a small woofer requires adding EQ to the amplifier which adds phase shift and group delay. Sound has magnitude and phase. This is why an out of phase pair of mains sounds the way it does. The amplitude is the same, but the phase is 180° out. The VECTOR sum is zero except for driver and room anomalies. So to integrate a sub, one needs both level and phase controls for the best VECTOR sum. A 180° polarity inversion is the equivalent of moving the sub ≈14 feet @ 40Hz. And a different distance for every other frequency.
Note that a phase control is not a perfect solution, it's just that it's next to hopeless without it.
See http://www.ielogical.com/Audio/SubTerrBlues.php for further explanation.
Tube Amps
=========
The REL instructions are either written for or by someone with ZERO understanding of output transformers.
Google stereophile phase in Images. Notice how the impedance rises in the low end of most speakers. With an output transformer, when the load impedance rises, SO DOES THE OUTPUT VOLTAGE. Since the REL SpeakOn input is high impedance, the sub output will increase due to the increased voltage even though the amplifier input signal does not change in level.
For the gazillionth time, roll the low end from the mains with a simple 6db/oct passive xover about ½ to 1 octave above the mains -db frequency and drive a sub with multiple XO slopes, phase and polarity controls into the LINE input.
Follow the interface guidelines under Setup at http://www.ielogical.com/Audio/SubTerrBlues.php.
There are links to model your room, main and sub placement. REW https://www.roomeqwizard.com/ also has good modelling.