Should I replace ARC D130 for Bryston 4B-ST?

I am running my Sony XA-7ES straight into the ARC D130 using the digital volume control of the Sony. My speakers are Sonus Faber Grand Pianos(not HOMES) and using Nordost Blue Heaven speaker cables.

I am satisfied with my current system but feel that the ARC D130 is lacking in the bass department (bottom end sounded loose and doesn't go too deep) and the highs are not too extended.

Do you think I should go for the 4B-ST? I was mainly aiming to get a more 'lively' sound and better bass with the Bryston.

Please advice as I have found a unit in the used market and it's just a matter of time before I buy it from the seller.

Also, do you think by getting a dedicated preamp like the BP-25 the sound will be further improved? I only listen to CD's and nothing else so I didn't consider getting a preamp at the moment. Will getting a dedicated preamp yield better results than running the CD player straight to the power amp?