Should I upgrade my receiver or sub?

[dicegames]

Current setup

• Receiver: Denon S760H
• Center: KEF R2c
• LR: KEF R3s
• Surround: KEF 350s
• Sub: SVS PB1000

I have $1k left in my budget and could either:

1. Upgrade the receiver to a Denon 3700 (with Audyssey MultEQ XT32 including LFC, which is intriguing as I have downstairs neighbors)

2. Upgrade Sub to PB1000 Pro which has a larger driver and room gain compensation (again, to help me at night with neighbors).

Which upgrade would benefit my setup more?

My use case is 40/40/20 gaming/movies/music. I have a relatively small room with 21ft vaulted ceilings, layout here -

https://imgur.com/a/TJ4M9Bk

 

[f1shb0n3]

1. Upgrade the receiver to a Denon 3700 (with Audyssey MultEQ XT32 including LFC, which is intriguing as I have downstairs neighbors)

I would upgrade receiver with Denon 3700 or Onkyo TX-RZ50, good room correction is essential and makes the biggest difference in listening experience.

Denon's LFC option just cuts low frequencies, you can do similarly with customizing the target curve in Audyssey or Dirac Live. That gets rid of the low body feel bass though, I wouldn't use it unless forced to.

2. Upgrade Sub to PB1000 Pro which has a larger driver and room gain compensation (again, to help me at night with neighbors).

Note that you can adjust the low bass with custom target curves with Audyssey or Dirac, this makes the SVS PEQ less valuable as a feature.
If you want bass quality improvement and especially making it more even across seats, adding a second sub is the best way to go.