  We analyse the implications of future observations of the CMB absolute
temperature at centimeter and decimeter wavelengths, necessary to complement
the accurate COBE/FIRAS data.
  Our analysis shows that forthcoming ground and balloon measures will allow a
better understanding of free-free distortions but will not be able to
significantly improve the constraints already provided by the FIRAS data on the
possible energy exchanges in the primeval plasma. The same holds even improving
the sensitivity up to ~10 times.
  Thus, we have studied the impact of very high quality data, such those in
principle achievable with a space experiment like DIMES planned to measure the
CMB absolute temperature at 0.5 - 15 cm with a sensitivity of ~0.1 mK, close to
that of FIRAS. Such high quality data would improve by a factor ~50 the FIRAS
results on the fractional energy exchanges associated to dissipation processes
possibly occurred in a wide range of cosmic epochs, at intermediate and high
redshifts (y_h > 1). The energy dissipation epoch could be also significantly
constrained, while the limits on the energy possibly dissipated at late epochs
can be improved by a factor ~2. In addition, such measures can provide an
independent and very accurate cross-check of FIRAS calibration. Finally, a
DIMES-like experiment will be able to provide indicative independent estimates
of the baryon density.
