  We present a technique to extract ultra-deep diffuse-light spectra from the
standard multi-object spectroscopic observations used to investigate
extragalactic globular cluster (GC) systems. This technique allows a clean
extraction of the spectrum of the host galaxy diffuse light from the same
slitlets as the GC targets. We show the utility of the method for investigating
the kinematics and stellar populations of galaxies at radii much greater than
usually probed in longslit studies, at no additional expense in terms of
telescope time. To demonstrate this technique we present Gemini/GMOS
spectroscopy of 29 GCs associated with the elliptical galaxy NGC 3923. We
compare the measured stellar population parameters of the GC system with those
of the spheroid of NGC 3923 at the same projected radii, and find the GCs to
have old ages (> 10 Gyr), [alpha/Fe]~0.3 and a range of metallicities running
from [Z/H] = -1.8 to +0.35. The diffuse light of the galaxy is found to have
ages, metallicities and [alpha/Fe] abundance ratios indistinguishable from
those of the red GCs.
