Logitech USB Speakers not working after upgrade to Yosemite

After upgrading my MacBook Air to Yosemite, my Logitech Z305 USB speaker no longer work. In fact, it isn't even recognized in the Output list in Sound in the System Preferences. It worked nearly all the time with Mavericks, with an occasional need for a system reboot if no sound was coming out, but it was always displayed under the Output tab regardless.

I just killed the coreaudiod process in the Activity Monitor, but this didn't do anything of note.

Any ideas of what has to happen for these speakers to work again?

Here are the system specs:

Host Controller Location: Built-in USB

Host Controller Driver: AppleUSBEHCI

PCI Device ID: 0x1c2d

PCI Revision ID: 0x0005

PCI Vendor ID: 0x8086

Bus Number: 0xfa

FaceTime Camera (Built-in):

Product ID: 0x850a

Vendor ID: 0x05ac (Apple Inc.)

Version: 6.46

Serial Number: CCGBCM031JDL8LLX

Speed: Up to 480 Mb/sec

Manufacturer: Apple Inc.

Location ID: 0xfa200000 / 3

Current Available (mA): 500

Current Required (mA): 500

Built-In: Yes

Hub:

Product ID: 0x2513

Vendor ID: 0x0424 (SMSC)

Version: b.b3

Speed: Up to 480 Mb/sec

Location ID: 0xfa100000 / 2

Current Available (mA): 500

Current Required (mA): 2

Built-In: Yes

BRCM20702 Hub:

Product ID: 0x4500

Vendor ID: 0x0a5c (Broadcom Corp.)

Version: 1.00

Speed: Up to 12 Mb/sec

Manufacturer: Apple Inc.

Location ID: 0xfa110000 / 5

Current Available (mA): 500

Current Required (mA): 94

Built-In: Yes