The S1 and the Z1 are for different people. The S1 has a built in power amp and more features but does not have the ES tweakiness (therefore better sound via line out). The Z1 is for those audiophiles that have a serious system and already have a great amp and or preamp/amp combo. The build quality of the Z1 is much better. Two serious transformers....dual mono 32 bit DACs, better output stages, better and more regulators, parts, etc. (all just for the DAC....not sharing power with an amp). You can see pics of the inside on the internet.
Imagine a company selling a $1000 integrated amp and then also has a $2000 preamp and a $2000 power amp.....You would hope the $4000 separates would sound better. This is what Sony is offering. They have a $2000 integrated amp that is the companion to the Z1.
Since there is room in the Z1 for mods then a modded Z1 could be really seriously great. Again, a different price point and different users.
Imagine a company selling a $1000 integrated amp and then also has a $2000 preamp and a $2000 power amp.....You would hope the $4000 separates would sound better. This is what Sony is offering. They have a $2000 integrated amp that is the companion to the Z1.
Since there is room in the Z1 for mods then a modded Z1 could be really seriously great. Again, a different price point and different users.