After spending an hour writing my really long post, I though I should backup what I say with what VIDA says.
So here's the VIDA information about the Radio, know as the IAM, for a 2013 V70. What they call an antenna "booster" is in fact the antenna amplifier:
Function
Audio unit
The integrated audio module (IAM) functions as a stereo system in the vehicle and is connected to other control modules on the MOS T network.
Integrated audio module (IAM) controls settings for:
- Volume
- Bass
- Treble
- Balance
- Fader
- Equalizer
Integrated Audio Module (IAM) has support for reception of digital HD-radio (High performance, High performance multimedia, and Premium sound multimedia). HD-radio is sent digitally on the AM and FM-band, respectively, in the USA. Integrated Audio Module (IAM) will automatically change to reception of digital HD-radio if it is available on the relevant frequency and of the function for HD-radio is selected in the user menu. When Integrated Audio Module (IAM) receives digital HD-radio, a symbol for HD-radio is shown in Infotainment control module (ICM).
The integrated audio module (IAM) lowers the volume from the current source when the control module receives other audio information, such as indication from the parking assistance function or phone call.
If the vehicle is equipped with a navigation system, voice information is played via the existing speakers.
Remote control
The steering wheel remote control (standard/option) is directly connected to the steering wheel switch right (SWSR). The remote control can be used to change volume (increase/decrease) and change the set radio stations. During playback of CD or USB/iPod the buttons are used for track selection. The steering wheel switch right (SWSR) communicates with the infotainment control module (ICM) via the LIN bus. ICM then sends the signals on to the integrated audio module (IAM) via the MOST network.
Design
Control module
Integrated Audio Module (IAM) is installed in the centre console.
The infotainment control module (ICM) display shows the current status of the integrated audio module (IAM).
The Integrated Audio Module (IAM) has integrated amplifier Base 2 x 20 W or Performance 4 x 20 W.
For versions that do not have an integrated amplifier, the Audio module (AUD) is used as an amplifier.
Aerials, integrated audio module (IAM)
V70, XC70, S80
Integrated Audio Module (IAM) is connected to an antenna system for AM and FM. The antenna system consists of an AM-antenna and two FM-antennas (FM1, FM2).
The antennas are located in the rear window. For XC60 (2011-) the AM and FM1 antennas are located in the tailgate's spoiler, the FM2 antenna is located in the right rear window.
AM and FM1 antennas are connected to an AM/FM antenna booster and the FM2 antenna is connected to an FM2 antenna booster. The antenna signals are sent from the antenna boosters to Integrated Audio Module (IAM) via two coaxial cables.
The antenna boosters are supplied with voltage from Integrated Audio Module (IAM).
Integrated Audio Module (IAM) with the option navigation is also connected to GPS-antenna and VICS-antenna (only Japanese market).
Remote control
Remote control via the steering wheel keypad is available as either an option or standard depending on the market. The keypad is on the right side of the steering wheel and is connected to steering wheel switch right (SWSR).
Loudspeakers
The Integrated Audio Module (IAM) for Base has four loudspeakers and Performance has six loudspeakers directly connected to the control module.
In each front door there are two speakers. The 2-way system consists of broad-banded bass/mid-range speakers and separate treble speakers. In both rear doors (Performance only) there is a broad-banded bass/mid-range speaker.
The impedance is 4 Ω for the base/mid range loudspeakers and 15 Ω for the treble speakers.
For versions without an amplifier, the loudspeakers are connected to the Audio module (AUD).
For more information, see Design and Function - Audio Module (AUD).
Microphone
The microphone is directly connected to the Integrated Audio Module (IAM). The microphone transmits analog signals to the Integrated Audio Module (IAM). The microphone has phantom-feed via Integrated Audio Module (IAM).
Telephone calls can be connected via the handsfree. The microphone and speaker are used for calls via the handsfree.