The MX.46xx for the first time offers 16 bit resolution synchronously on four channels at very high sampling rates. Every channel has its own amplifier and A/D converter. This eliminates the problems known from multiplexed systems like phase error between the channels or high crosstalk. Every input channel can be offset and gain calibrated by software using a highprecision onboard calibration source. The user will easily find a matching solution from the eight offered models. These versions are working with sampling rates of 200 kS/s, 500 kS/s, 1 MS/s or 3 MS/s. The boards can also be updated to a multichannel system using PXI backplane signals. Based on the CompactPCI 3U standard the PXI (PCI eXtensions for Instrumentation) enhancement was defined especially for the measurement user. In this specification additional lines for measure ment purposes are defined. There is a high-quality 10 MHz reference clock, as well as a star trigger and a trigger bus. The Spectrum boards support all these features, most notably with the help of the reference clock and the star trigger module for an easy combination of products - in including those from different companies. Since September 2003 Spectrum is a member of the PXI system alliance. The Spectrum PXI cards run in a plain CompactPCI 3U slot as well as in a dedicated PXI 3U slot. If using the MX series in a plain CompactPCI slot the PXI features will not be available.