Update on Sola/USB OTG Power Consumption Error:
I think I have a faint clue as to why a cheap USB DAC inserted between Xperia Sola and a USB Device may solve the Power Consumption Error.
I checked Windows Device Manager properties/Power tab for USB devices connected to my laptop, and here are the findings:
1) A USB Flash Drive, that was rejected by Sola if plugged straight into the OTG cable:
I know it's cyrillic, but the highlighted item is Mass Storage Device, and it claims it needs 500mA.
2) Another USB Flash drive, that was accepted and mounted by Sola, plugged directly to USB OTG:
As you can see, the USB Mass Storage Device claims it needs only 200mA!!! Which means that Sola is willing to provide 200mA, but not 500mA. I guess the threshold is somewhere between these two values, but I have no way to tell the exact value.
3) RSA Predator - rejected by Sola if plugged directly into USB OTG:
The highlighted item says USB Composite Device (which is how RSA Predator reports itself to the host PC), and (unfortunately) it claims it needs 500mA of current. I know for sure that this is not true: Ray Samuels, while not going into specific details, told me that the Predator's USB power consumption is "far less than 100mA", and I have no reasons not to believe him. The Predator only uses USB to power the DAC cirquit, the entire amp section is powered by the built-in Lithium battery. And this is a very sad thing, because not only it reduces Predator's compatibility with power-avarious android devices, but I also think this is one of the reasons why it is incompatible with Apple CCK, because it calls the same error message: "the device consumes too much power". Which it does not in reality...
And finally, the icing on the cake: 3$ generic USB hub!
Bingo!!! The highlighted item says... well, you see what it says, it's in English :-) But look at the right column value: 0!!! The device tells the host that it needs no current at all!!!
This brought me to an emperical, not science-backed conclusion that a USB hub (or at least certain types of USB hubs) is not transparent for Android USB OTG host device, such as Xperia Sola, and, in case it reports 0mA power reqiuirements, you can plug a coffee machine into it, and still have it accepted by your phone.
Disclaimer: a coffee machine was a joke. And if you burn something plugging things all over the place after reading this post - don't hold me responsible! :-)