Well, these devices (both the BTR3 and BTR1k) are bluetooth rigs. As such, with the Iphones (which is what I have as well) they use the AAC codec for transmitting music, which isn't technically lossless right? But, assuming the iphone XS has similar output power to the iphone7 (which I have) the BTR1k absolutely provides a nice volume boost. It's a more powerful amp than the iphone's. Anything up to maybe 64ohm buds would be able to reach ear-shredding volume I'd think... and even though it isn't lossless, it sounds very very good. Actually, I'd imagine the DAC in the BTR1k is probably better than the iphone dongle as well.