Zu Def III system upgrades

Folks,

I had explored previous threads, but wanted to get some updated input based on updates to my system (see below).

I've been pretty content with the system for many years. The upgrade to the Topping DAC took the system to another level with the amount of detail and soundstage holography. My recent add was the Event XLRs (taking advantage of Zu's recent sale) to take the place of an older Zu interconnect between amp and preamp. Even though the interconnect is not fully broken in, the major impact in detail, sound staging and even loudness was as noticeable as an electric upgrade. Quite startling. The Event / Varial combo seem to work well

General question(s):

   a) is it worth getting a second Event XLR for preamp / DAC?

  b) worth getting one of Zu's SPDIF cable?

Any other upgrades including updates to the Def IIIs

Many thanks

Currently I have:

- Zu Def III speakers (Sean did the install 2012) / IBIS speaker cables / Mission power cords for the speaker

- Balanced Audio Technology VK-55 SE power amp / using new Event XLR to preamp

- Balanced Audio Technology VK-3ix SE / using Varial XLR to DAC

- Topping E50 DAC

- Oppo BDP-95 Disc player