My Azur 540C cd player has four of those monolithic voltage regulators: two 7805's one 7815 and one 7915. The 7805's supply the clock and the DAC with 5 volts. The 7815 and the 7915 supply the opamp with symmetrical 15 volts.
I made my voltage regulators on pieces of stripboard. A quick check showed they all work. I removed all the old voltage regulators and replaced them with my boosted regulators. While I was at it I also replaced the bog standard 1N4002 rectifier diodes with 11DQ10's.
How does it sound now? A very nice improvement in soundstaging, the treble really sparkles without being harsh. Worth it? IMO, yes these cheap to make regulator boosters provide a pretty nice upgrade.