Midisoft studio 4 (32bit version) may run on x64 host.
You need copy mmsystem.dll (resides in c:\windows\system32\) from windows 7 32bit host to c:\windows\SysWOW64 on your 64bit system (win7 or win8.1) under Administrator account.
Also in the setup->MIDI drivers dialog set "Do not use MIDI...