So it comes down for under $500. The Hiby R6, Ibasso 150, the Shanling m5s.
Are we convinced the m5s can compete with the highly rated r6 and the 150?
I'll say yes the M5s is going to compete fairly solidly. The R6 has a lot of great features but honestly the m5s matches most of those so it will come down to UI responsiveness and implementation for most people. (The M3s already sounded pretty darned good so if they tweaked a bit the M5s should rock). Where the M5s really could one up the R6 is in battery life where the M5s shows potential for all day use while the R6 realistically appears to be a 4-6 hour player in most use cases.
The DX150 brings the ability to swap amp modules but that also increases the cost by $200 for each additional module you add so really makes this an unfair comparison. If you stick with the stock amp provided with the unit, the Dx150 and M5s have similar specs and again it is likely to come down to personal choices as to which each person likes better.