I am just beginning my adventure into the world of audio. I'm thinking my listening will be 60% Music, 40% Movies.

The only space I have available for a designated listening room is in my basement which has 6 foot ceilings. the dimensions of the room is 14'x13'x6' with three of the walls being concrete foundation. I felt confident in my decision to start with a pair of Bower Wilkins 603 s2 Anniversary speakers and Denon AVR-X4700H. I'm thinking of using a Topping DX7 Pro ES9038Pro Dac from my computer to the AV receiver to play my Amazon Music HD and an Apple TV 4k into my AV receiver for movies.

An opportunity just presented itself to buy a pair of Bower & Wilkins CM9 S2 speakers in perfect condition. Would I be better off sticking with the 603 Anniversary speakers or getting the older CM9 speakers. Money aside which is the better speaker. I don't want to spend more than what it would cost to get the 603s.

My second question is should I go with that Dac knowing also using it as a Audio Interface for less important recording capabilities or get something like the Cambridge Audio DacMagic Plus-BK.

The ceiling of the room and exiting wall will be outlined using Audimute sound blocking material. Are there any disadvantages of having an acoustically sealed room?

My last question is very broad. I have no clue which sub to get for such a small room. I love deep bass but I dont really care if really care if the entire home is shaking. Id rather have quality low range sound than a lot of movement.

You guys are awesome. This is my first post and look forward to hearing what you guys think.