I create sample-based kits and noticed that a sample's volume in Spark is about half the native volume. As noted in another forum topic, this is a known issue with the either the built-in sampler module, or as I may have discovered, partly the default modular patch that Spark creates. Please see the attached screenshot of the patch I am using. I am not a modular guy, so I can't say whether this is set up intelligently, but regardless, it works for me. At maximum velocity, my samples now play at about -5db compared to the native sample volume in Logic Pro X. (I have to drop the fader on the native sample 5db to match the output). This is MUCH better and it is a volume I can actually work with both for production and performance. I have also included a Spark preset that contains 16 empty sample instruments that are all set up with this modular patch. This has saved me tons of time figuring out volume! Give it a try, I hope it works for you too!