  In this paper we study the spectral efficiency (SE) of a point-to-point
massive multiple-input multiple-output system (P2P-massive MIMO) with limited
radio frequency (RF) chains, i.e., analog-to-digital/ digital-to-analog
(D2A/A2D) modules, at the transceivers. The resulting architecture is known as
hybrid beamforming, where the joint analog and digital beamforming optimization
maximizes the SE. We analyze the SE of the system by keeping the number of
RF-chains low, but placing analog amplifiers at different paths. Conventional
hybrid beamforming architecture uses the amplifiers right after the D2A
modules. However, placing them at the phase shifters or at the antennas can
effect the SE of hybrid beamforming. We study the optimal placement of the
analog amplifiers and pinpoint the amount of loss in case of misplaced
amplifiers.
