The VL Design TEF25 USB Preamp combines the portability of a small USB Preamp with the accuracy of the traditional TEF20 analyzer, in an affordable package. The TEF25 comes with the SoundLab SLUPG1 Software Upgrade that lets you run all previously owned TEF20 programs: TDS, MLS, RTA, PEQ, PLR and SLX. Run the older Versions or step up to Version 6 modules! Available in Version 6 is the Post Processing Module, SLPPS60. Also included is the TEF Training Class 3-DVD Set that contains the topics from the TEF Level I class.