Why put a crossover between your preamp and amp?

[ex audiophile]

I was reading a review of the Focal Spectral 40th floorstanders (Soundstagehifi.com by Diego Estan) and was intrigued by the setup used by the reviewer.

"I connected the 40ths to the 8-ohm output taps of my McIntosh Laboratory MC302 power amp. Upstream, I used a Bluesound Node streamer as a source, connected via fiber-optic interconnect to a miniDSP DDRC-22D processor with its Dirac Live room correction turned off, its digital volume control set to maximum and its digital output connected via a TosLink optical link to the DAC in my McIntosh C47 preamp. The C47 was connected to the MC302 via balanced (XLR) interconnects through my two SVS SB-4000 subwoofers, both turned off. (The SB-4000s’ line-level outputs are internally straight-wired to their inputs.) When the DDRC-22D is in the signal chain with Dirac Live turned off, the miniDSP merely upsamples all incoming PCM data to 24-bit/96kHz. The Node, used as a Roon endpoint, was operated via the Roon Remote app installed on a Samsung Galaxy Tab S; the Roon Core software was installed on a laptop computer running Windows 10."

I get the gist of this but have no experience with Roon and have no idea what he meant by the comment that his C47 preamp was connected to his amp "through my two SVS SB-4000 subwoofers, both turned off." In his list of associated equipment he includes a crossover that he used in between his preamp and amp:

Associated Equipment

• Speakers -- Bower & Wilkins 705 S2
• Subwoofers -- SVS SB-4000 (2)
• Power amplifier -- McIntosh Laboratory MC302
• Crossover -- Marchand Electronics XM446XLR-A (between preamp and amp)
• Preamplifier-DAC -- McIntosh Laboratory C47
• Room correction EQ -- miniDSP DDRC-22 with Dirac Live (between digital sources and DAC)
• Digital sources -- Rotel RCD-991 CD player, Bluesound Node streamer, laptop computer running Windows 10, Roon Core
• Analog sources -- Pro-Ject Debut Carbon Esprit turntable with Ortofon 2M Red cartridge
• Speaker cables -- 12-gauge, oxygen-free copper (generic, locking banana plugs)
• Analog interconnects -- AmazonBasics unbalanced (RCA), Monoprice Premier series balanced (XLR)
• Digital interconnect -- AmazonBasics optical (TosLink)

I was pleased to see that he used basic cables but I do not understand the use of a crossover this way. If anyone would care to clarify this for me I'd appreciate it.

 

[617]

I doubt he is using the marchand PLLXO (rarely see PLLXO, crazy stuff). The subs probably have the ability to high pass the signal to the main speakers, but since they are turned off they aren't doing that. It sounds like he is running the focals full range through many extraneous pieces of equipment.

 

[ex audiophile]

thanks, sounded a bit bizarre to me. the speaker review was otherwise helpful in that i had to look up sibilant (again) lol