Generally speaking, to obtain the maximum output of a speaker to be used without clipping the amp, you can choose an amplifier that can deliver the same power as the PGM power rating of the speaker. If the PGM power rating is not described, the reference value is half the MAX/peak power rating (or twice as much as the NOISE/continuous power rating). For example, when driving 2 units of S115V speaker (PGM 500W @ 8 ohms) with the P-S series amp, P5000S (525W x 2 @ 8 ohms) is suitable to obtain the maximum output of the speaker. However, your required output power differs depending on the type of source signals and required sound pressure level in addition to the speakers to be used. For example, while a momentary clipping that can hardly be felt does not generally matter, in demanding applications such as studio monitoring system, where even a brief moment of clipping is not allowed, you may be required to choose an amp with higher output power. Also, if your application is background music in an installed sound system where the required sound pressure level is low, you may choose an amp with lower output power. However, if using a lower-power amp, please be careful not to drive the amp into clipping. Even if the output power of your amp is lower than the power rating of a speaker, clipping the amp can damage the speaker driver easily.

As of April 2011, power amplifiers supporting a high-impedance connection are as follows.

A high-impedance speaker connection, which is used for the distributed speaker system in many installations, allows numerous speakers to be connected to a single power amp, and to perform long-distance transmission. A speaker transformer that raises the impedance to several hundred or thousand ohms is added to the speaker. This allows the speaker to be effectively driven with much lower current than is required for a low-impedance system. That, in turn, makes it possible to connect a larger number of speakers in parallel to each power amp output. High-impedance speaker connections work at a specific maximum voltage - usually 70 or 100 volts - and are therefore also referred to as "constant voltage" speaker systems (the label "constant voltage" is somewhat misleading: the actual output voltage fluctuates according to the input signal).

As of April 2011, the following six models support 2-ohm drive: TX6n, TX5n, TX4n, T5n, T4n, and T3n The specifications of the PC-1N and XP series show the dynamic power output at 2-ohm load (20ms). However, this does not guarantee the continuous use under a 2-ohm load. Depending on the source signal type, the amps may be able to be used at 2-ohm load if the signal level is within the level where audio clipping only rarely occurs. However, there may be the case where the amps are continuously driven only by fewer than half the output power at 4-ohm load.

Power consumption measured at 1/8 output is described in the Specifications page (Products>Power Amps>(Each amp page)>Specifications). 1/8 output (9dB lower than the maximum) is an assumed condition where an ordinary music signal clips occasionally. This value can be used as a reference to estimate the required power supply capacity. However, if the amp is driven into clipping continuously or the source music signal is extremely compressed (narrow dynamic range) and level-maximized, it may require approximately twice the value.

EEEngine is a Yamaha's proprietary amplifier driving technology that delivers Class AB sonic performance with highly efficient power consumption. For details, please refer to the following page:

The 5-way binding post is a terminal that allows the connection of several different types of connectors such as bare wire, Y-plug, and banana plug. The 5-way binding post and speakON connectors are internally connected in parallel and can be used at the same time. When you connect speakers to the amp using both connectors, be careful of the speaker load. (When connecting two speakers of 4 ohms in parallel, the speaker load becomes 2 ohms.)

Yes. Audio signal can be sent through either connector because the XLR connector and phone connector are internally connected in parallel. However, audio signals cannot be mixed by inputting the signals from both connectors. If your amp has an XLR connector and Euroblock connector for the input, audio signal can be sent through either connector as well.